Production methods of pattern thin film, semiconductor element, and circuit substrate, and resist material, semiconductor element, and circuit substrate

ABSTRACT

The present invention provides production methods of a pattern thin film, a semiconductor element and a circuit substrate, capable of eliminating the number of photolithography processes needed for patterning; and a semiconductor element, a circuit substrate, and an electron device obtained by the production methods. The production method of the pattern thin film of the present invention is a production method of a pattern thin film, comprising the steps of: forming a first resist pattern film on a thin film formed on a substrate; forming a second resist pattern film; patterning the thin film using at least the second resist pattern film, wherein in the step of forming the second resist pattern film, a fluid resist material or an organic solvent is applied on a groove of a bank pattern formed using the first resist pattern film.

TECHNICAL FIELD

The present invention relates to production methods of a pattern thinfilm, a semiconductor element, and a circuit substrate, and a resistmaterial, a semiconductor element, a circuit substrate, and an electrondisplay. More specifically, the present invention relates to: a patternthin film-producing method preferable for production of a fine patternthin film; a semiconductor element-producing method preferable forproduction of a thin film transistor and the like; a circuitsubstrate-producing method preferable for production of an active matrixsubstrate and the like; a resist material preferably applied with aninjection device such as an ink jet device; a semiconductor element suchas a thin film transistor; a circuit substrate such as an active matrixsubstrate; and an electron device such as an imaging device, an imageinput device, and a display device.

BACKGROUND ART

Photolithography is generally employed if a precise pattern wiring or afine pattern thin film used in a display application and the like needsto be formed with high accuracy on substrates such as a semiconductorsubstrate typified by a silicon (Si) substrate, a glass substratetypified by an alkali glass substrate and a non-alkali glass substrate,a glass-epoxy substrate used as a print wiring substrate, a flexiblesubstrate, and a plastic substrate widely used in a display applicationand the like.

In common photolithography, a resist material having photosensitivity(photoresist material) is first applied over the entire surface of thesubstrate and thermally treated to form a resist film. Then, the resistfilm is exposed using an exposure device such as a step type projectionexposure device (stepper) and a photomask having a specific pattern.Then, development is performed using a developer containing an organicalkali and the like, and thereby a resist pattern film is formed on thesubstrate. Then, using this resist pattern film as a mask, the substrateis exposed to etching atmosphere by a wet-etching method or adry-etching method. As a result, the thin film on the substrate isprocessed to have a specific pattern. The resist pattern film is removedby a remover containing an organic solvent and the like at anappropriate stage.

In such photolithography, it is advantageous for the production that thenumber of times the resist pattern is prepared is reduced as much aspossible. Attempts to reduce the number of times the resist pattern filmis prepared by optimizing a structure of a desired device, wiring, andthe like, have been made so far, and attempts employing an exposuremethod also have been made.

For preparation of a TFT (Thin Film Transistor) array substrate used ina liquid crystal display device and the like, a method of locallythinning a resist pattern film using a photomask having a slit pattern(halftone exposure method) was proposed (for example, refer to NonpatentDocument 1). In this case, the resist pattern film is formed and then afirst etching treatment is provided for the substrate. Then, the resistpattern film at a halftone exposure part is removed, and a secondetching treatment is further performed. If the thin film on thesubstrate is subjected to the two-step process in such a manner, thenumber of photolithography processes which is generally twice can bereduced to one, although the pattern is restricted, in comparison to thecase where the photolithography process is simply performed twice. Sucha halftone exposure method is employed to form a TFT channel inNonpatent Document 1.

A method using such a halftone exposure method and a reflow method incombination was also disclosed (for example, refer to Patent Document1). This is a method in which a resist pattern is left to have an islandshape near a source electrode and a drain electrode, and then deformedusing organic solvent steam, thereby forming a semiconductor having anisland shape.

It has been recently proposed that an ink-jet technology which has beendeveloped in a printer application is used for preparation of circuitsubstrates. This is a technology of forming a metal film having apattern and the like directly on a substrate by an ink-jet method. Ithas been proposed that this technology is used for preparation ofwirings or passive elements (condenser, resistance, inductor, and thelike). In this technology, a droplet containing metal fine particles forpreparation of wirings or a droplet containing a metal oxide materialand the like for preparation of condensers and the like, is addeddropwise with an ink-jet device, and thereby wirings and/or passiveelements are formed at a specific position on a substrate (for example,refer to Nonpatent Document 2).

A technology of forming an insulating layer or a passivation insulatinglayer in a TFT (thin film transistor) by applying a fluid material andperforming heat treatment was disclosed (for example, refer to PatentDocument 2).

In the ink-jet method, a method of providing a substrate with apretreatment in advance before addition of a droplet also has beenproposed. Such a method is aimed to reduce position accuracy when anadded droplet is landed on the substrate (landing accuracy) or toimprove the process speed by reducing the number of needed droplets. Inthis technology, a region showing lyophilicity for a material forforming a wiring and a region showing lyophobicity for it are formed ona substrate where the wiring is formed, and a droplet of the materialfor forming a wiring is added into the lyophilic region by an ink-jetmethod (for example, refer to Patent Document 3). An exposure device, aphotomask, and the like are used for forming these lyophilic andlyophobic regions.

In addition, it is also disclosed that similarly in the wiring-formingtechnology by an ink-jet method, a bank is formed to surround awiring-formed region and an upper part of this bank is provided withlyophobicity and the wiring-formed region is provided with lyophilicity,in order to suppress the material for the wiring from flowing out of thewiring-formed region (for example, refer to Patent Document 4). Also inpreparation of this bank, a resist material having photosensitivity, anexposure device, a photomask, and the like, are used.

A technology of forming a TFT using only organic matters by an ink-jetmethod was also disclosed (for example, refer to Nonpatent Document 3).

If such an ink-jet method is used, a fluid material that is a materialfor a film to be formed is needed. However, a special production methodis needed in order to obtain a film having characteristics equal tothose of a film formed using a conventional vacuum deposition device, bya sputtering method or a CVD method. Therefore, such a method has notreplaced the conventional method yet.

Further, it has been also proposed that using an ink-jet method, not thefluid material that is a material for a film to be formed but a resistmaterial for forming a mask used when processing a thin film and thelike on the substrate is added dropwise. This is a method of patterninga semiconductor layer of a TFT using a resist film which is formed bydropwise addition with an ink-jet method as a mask (for example, referto Patent Document 5).

A TFT array substrate may be mentioned as a circuit substrate preparedthrough many photolithography processes, for example. The TFT arraysubstrate includes a source wiring, a gate wiring, a TFT as a switchingelement connected to these wirings on a substrate, and is preferablyused in a liquid crystal display device, and the like, for example. ThisTFT array substrate is produced through a series of steps shown inNonpatent Document 4, and five or more photolithography processes aregenerally needed for production of the TFT array substrate.

[Patent Document 1]

Japanese Kokai Publication No. 2002-55363

[Patent Document 2]

WO 97/43689

[Patent Document 3]

Japanese Kokai Publication No. Hei-11-204529

[Patent Document 4]

Japanese Kokai Publication No. 2000-353594

[Patent Document 5]

Japanese Kokai Publication No. 2004-247704

[Nonpatent Document 1]

C. W. Kim, et al., “A Novel Four-Mask-Count Process Architecture forTFT-LCDs”, SID 00 DIGEST, (U.S.), Society for Information Display, 2000,vol. 31, first edition, p. 1006 to 1009.

[Nonpatent Document 2]

Nikkei electronics, issued on Jun. 17, 2002, Nikkei BusinessPublications, Jun. 17, 2002, No. 824, p. 67 to 78.

[Nonpatent Document 3]

Takeo Kawase, et al., “Invited Paper: All-Polymer Thin Film TransistorsFabricated by High-Resolution Ink-jet Printing”, SID 01 DIGEST, (U.S.),Society for Information Display, 2001, vol. 32, first edition, p. 40-43.

[Nonpatent Document 4]

Nikkei Micro Device edition, “Flat Panel Display 1999”, Nikkei BusinessPublications, 1998, p. 129.

DISCLOSURE OF THE INVENTION

As mentioned above, the photolithography is generally used forproduction of a pattern thin film on a substrate, particularly if a finepattern or high accuracy is needed. Examples of common disadvantages ofuse of the photolithography include that a large amount of chemicalssuch as a resist material, a developer for development, a resist removeris used because a resist material having photosensitivity is applied onthe entire surface of a substrate; and that a high-accuracy device isneeded as a device for applying the resist material, an exposure device,and the like. Therefore, the use of the commonly used photolithographyinvolves increase in environmental loads, material costs, and/or largeequipment investment costs. Therefore, reduction in the number ofphotolithography processes is an important problem in production ofcircuit substrates or devices.

Particularly in production of a TFT array substrate, reduction in thenumber of photolithography processes is an important issue because manythin films are formed on a large substrate. In such a TFT arraysubstrate production, as mentioned above, reduction in the number ofphotolithography processes by a halftone exposure method has beenproposed, for example, as in Nonpatent Document 1. However, in thehalftone exposure method, it is difficult to stably form a resist filmhaving a desired shape and film thickness at a halftone exposure partbecause exposure conditions and developing conditions are difficult tocontrol. Therefore, if a TFT channel is formed by the halftone exposuremethod, as in Nonpatent Document 1, the shape of the TFT channel formedat the halftone exposure part tends to vary in the substrate surface andan internal capacitance of the TFT part, that is, a capacity betweenelectrodes of the TFT, for example, a capacity between a gate electrodeand a drain electrode, tends to vary. Further, the resist pattern filmon the entire substrate is retreated when the resist film at thehalftone exposure part is removed. This retreat degree tends to vary inthe substrate surface. Accordingly, a width of a wiring such as a sourcewiring, formed using this retreated resist pattern film as a mask, alsotends to vary. Such variation tends to cause display unevenness if a TFTarray substrate is prepared by this method and used in a display device.Therefore, such a method has room for improvement. Therefore, aconventional halftone exposure method such as the method disclosed inNonpatent Document 1 is not a method commonly used for forming ahigh-definition pattern thin film.

Also according to a method using the halftone exposure method and thereflow method in combination, as in Patent Document 1, the number ofphotolithography processes can be reduced, but sufficient patternaccuracy can not be obtained if a resist pattern film is formed by thehalftone exposure method. Therefore, this method has a difficultyparticularly in stable formation of a high-accuracy pattern in a TFTarray substrate. Accordingly, if this method is used to produce a TFT,element characteristics vary among TFTs depending on position variationand/or shape variation. In this point, such a method has room forimprovement.

In addition, in a system of adding dropwise a resist material by anink-jet method, thereby forming a mask for process, as in PatentDocument 5, the number of photolithography processes can be reduced, butcan not provide sufficient landing accuracy of a resist droplet addedusing an ink-jet device, particularly if a fine pattern or high accuracyis needed in production of a TFT array substrate, and the like.Therefore, such a system is difficult to use. Accordingly, if thismethod is used for producing a TFT, element characteristics vary amongTFTs depending on position variation and/or shape variation. In thispoint, such a method has room for improvement.

The present invention has been made in view of the above mentioned stateof the art. The present invention has an object to provide: productionmethods of a pattern thin film, a semiconductor element and a circuitsubstrate, which can reduce the number of photolithography processesneeded for patterning; a resist material used therein; and asemiconductor element, a circuit substrate, and an electron device,obtained using the production methods.

The present inventors made various investigations on production methodsof a pattern thin film, which can reduce the number of photolithographyprocesses needed for patterning. The inventors noted a first resistpattern film formed in a first photolithography process in thephotolithography process which is conventionally performed twice, andnoted that a thin film after etching performed using the first resistpattern film as a mask is used in a second photolithography process. Theinventors found that if a fluid resist material is applied on a grooveof a bank pattern formed using the first resist pattern film in a stepof forming a second resist pattern, the second resist pattern can beformed with high accuracy even by coating and the secondphotolithography process can be omitted. Therefore, the inventors foundthat in formation of a semiconductor element such as a thin filmtransistor, for example, if a resist pattern film is formed by applyinga fluid resist material inside a channel groove formed above a channelregion after channel etching or inside a resist groove formed using thefirst resist pattern film above a channel region before channel etchingin a process of forming a multilayer structure of a source electrode, adrain electrode, and a semiconductor layer constituting thesemiconductor element with a semiconductor layer, a conductive film anda semiconductor film are patterned through one photolithography process,and thereby a multilayer structure of the source electrode, the drainelectrode, and the semiconductor layer can be formed, and in addition,the shape variation among the semiconductor layers can be sufficientlysuppressed and the characteristic variation among the semiconductorelements can be sufficiently suppressed. As a result, theabove-mentioned problems can be admirably solved, leading to completionof the present invention.

That is, the present invention is a production method of a pattern thinfilm, including the steps of: forming a first resist pattern film on athin film formed on a substrate; forming a second resist pattern film;patterning the thin film using at least the second resist pattern film,wherein in the step of forming the second resist pattern film, a fluidresist material is applied on a groove of a bank pattern formed usingthe first resist pattern film.

In the present description, the pattern film is not especially limitedas long as it is a film having some kinds of a planar shape (pattern)other than a film formed on the entire substrate, and may consist of onelayer or two or more layers. It is sufficient that the above-mentionedresist pattern film is a pattern film which does not remain in the laststate after completion of the production steps. Such a resist patternfilm is formed on a thin film and can be used as a mask for processing(patterning) the thin film. The above-mentioned resist pattern film maynot be necessarily prepared using a resist material havingphotosensitivity (photoresist material), a photomask, and the like. Thatis, the above-mentioned resist pattern film may be a film formed using aresist material having photosensitivity (photoresist material) or may bea film formed using a resist material not having photosensitivity.Therefore, for example, the first resist pattern film may be formed by aphotolithography technology using a resist material havingphotosensitivity and a photomask or simply formed by a printing methodsuch as a screen printing.

The pattern thin film produced in the present invention is notespecially limited as long as at least one thin film formed on thesubstrate is formed by patterning using at least the second resistpattern film, that is, by a treatment of changing the planar shape(pattern), and is not limited by its thickness. Therefore, the patternthin film produced in the present invention may have a film thicknesssmaller than that of the first resist pattern film or the second resistpattern film.

The above-mentioned bank pattern means one which includes a structurehaving a height (bank) and a depression (groove) formed between thestructures and has a planar shape (pattern) capable of exhibiting afunctional effect of suppressing the fluid material from spreading.Specifically, the above-mentioned bank pattern formed using the firstresist pattern film includes: (1) a bank which is the first resistpattern film, (2) a bank which is a first resist pattern film-includingpattern film formed by etching using the first resist pattern film as amask, or (3) a bank which is a pattern film formed by performing etchingusing the first resist pattern film as a mask and removing the firstresist pattern film; and a groove corresponding to such a bank.

According to the present invention, the shape of the second resistpattern film can be controlled using the first resist pattern film. Thefirst resist pattern film can be a control pattern for controlling thepattern after the resist material is added dropwise if an appropriatefirst resist pattern is previously disposed near the position where theresist material for forming the second resist pattern film is addeddropwise. In such a case, a region on the substrate where the firstresist pattern film is formed and a region on the substrate where thesecond resist pattern film is formed have a mutually overlapping regionand/or a mutually connecting region.

In the present invention, the first resist pattern film is prepared by amethod such as photolithography, and the second resist pattern film isfurther formed by application on the substrate. Accordingly, thetwo-step patterning process can be provided for the thin film on thesubstrate, and therefore in some thin film patterns to be formed, aprocess that is equivalent to two photolithography processes can beperformed. In addition, the second resist pattern film is formed byselectively applying the fluid resist material on the groove of the bankpattern on the substrate. Therefore, loss of the resist material can bereduced in comparison to the case where the resist film is formed on theentire surface of the substrate and then patterned to form a resistpattern film. Further, neither exposure step nor developing step isneeded and therefore a photomask, an exposure device, and a developercan be reduced. That is, the pattern is restricted in some cases, but ifa desired pattern can be formed by the method of the present invention,two photolithography processes can be reduced to one, which can alsoreduce the exposing steps and the developing steps to one. Therefore,the present invention permits reduction in environmental loads, materialcosts, and equipment investment costs, in the production (process) ofthe thin film.

Specific examples of the method according to the present inventioninclude a method in which after the first resist pattern film isprepared, a patterning (etching) process is provided for the thin filmon the substrate, and then the second resist pattern film is formed anda patterning (etching) process is performed. According to this, the thinfilm on the substrate can be processed to have a pattern having twoportions with different film thicknesses. The second resist pattern filmmay be prepared to have a thickness smaller than that of the firstresist pattern film, when the first resist pattern film is prepared andsuccessively the second resist pattern film is prepared. In this case, aresist pattern film equivalent to a film formed by a half exposuremethod in which the substrate surface is exposed using different lightamounts can be obtained. Also in this case, the two-step patterningprocess can be provided for the thin film on the substrate.

Preferable embodiments in the production method of the pattern thin filmaccording to the present invention are mentioned below.

It is preferable that the bank pattern has an open end. That is, it ispreferable that not the entire outer edge of the above-mentioned grooveof the bank pattern is surrounded by the bank. In such a case, even ifthe fluid resist material applied on the groove of the bank patternslightly flows outside of the groove of the bank pattern immediatelyafter applied, the resist material can be kept inside the groove of thebank pattern by surface tension of the resist material when the resistmaterial is dried. Preferable embodiments of the bank pattern having anopen end include an embodiment in which the bank pattern has a pair ofbanks and an open end is disposed on the both ends side of the bank. Inthis case, the resist pattern film can be formed by a method of addingthe fluid resist material into a space between the pair of electrodes.For example, a thin film element such as a thin film transistor (TFT)can be produced through a smaller number of steps in comparison to aconventional method.

It is preferable that the thin film formed on the substrate includes twoor more layers. For example, a thin film formed by stacking a metallayer and a semiconductor layer is preferably used in production of asemiconductor element. Accordingly, a part of the element can be formedusing a plurality of layers made of substances having differentelectrical characteristics.

It is preferable that in the step of forming the first resist patternfilm, a resist material having photosensitivity is used and exposure isperformed using a photomask. In this case, the first resist pattern filmis formed by a very high-accuracy method, and therefore can function asa control pattern used in formation of the second resist pattern film,with accuracy. Therefore, the second resist pattern film with highaccuracy can be formed. As a result, a semiconductor element such as athin film transistor, which has high accuracy and characteristics hardlyvaried, can be prepared. A resist material having photosensitivity or aresist material not having photosensitivity may be used as a materialfor the second resist pattern film.

It is preferable that the production method of the pattern thin filmincludes a plasma surface treatment step between the step of forming thefirst resist pattern film and the step of forming the second resistpattern film. That is, in the present invention, the second resistpattern film is formed by selectively applying the resist material, andtherefore it is preferable that a surface treatment is previouslyprovided for the substrate before the application to adjust a lyophilicor lyophobic property for the resist material. As a result, the resistmaterial that is a material for the second resist pattern film isprevented from conforming to the substrate surface and spreadingexcessively, and thereby the second resist pattern excellent incontrollability can be formed. It is preferable that the plasma surfacetreatment step is performed in fluorine gas plasma. According to this, asurface having an excellent lyophobic property can be formed. Theabove-mentioned fluorine gas is not especially limited as long as it isa gas composed of a fluorine atom-containing compound. Carbontetrafluoride and the like may be mentioned as such a fluorine gas.

It is preferable that the production method of the pattern thin filmincludes a step of patterning the thin film using the first resistpattern film between the step of forming the first resist pattern filmand the step of forming the second resist pattern film. That is, thethin film on the substrate is patterned (etched) using the first resistpattern film before formation of the second resist pattern film. If thethin film on the substrate is subjected to the two-step process, such amethod improves production efficiency because an etching treatment timecan be reduced. It is preferable that the step of patterning the thinfilm using the first resist pattern film is performed by a dry-etchingmethod. In this case, the surface treatment can be successively providedfor the substrate in the same vacuum chamber after the dry etching, andtherefore there is no need to additionally perform the surface treatmentstep. Therefore, such a method is efficient.

An embodiment in which the production method of the thin film includes astep of removing the first resist pattern film between the step ofpatterning the thin film using the first resist pattern film and thestep of forming the second resist pattern film may be mentioned as apreferable embodiment of the present invention. If the second resistpattern is formed to be contact with or very closely to the first resistpattern film, the first resist pattern film may be deformed or dissolvedby a solvent contained in the resist material for forming the secondresist pattern film. Therefore, in some cases, the first resist patternfilm should be removed. For formation of the second resist pattern film,the thin film processed to have a shape of the first resist pattern filmcan be used as a pattern for controlling the resist material selectivelyadded dropwise, by utilizing the difference in thickness or material.Therefore, the controllability of the second resist pattern film can beimproved even if the first resist pattern film is removed.

An embodiment in which the production method of the pattern thin filmincludes the steps of: after the step of forming the first resistpattern film and the step of forming the second resist pattern film,patterning the thin film using the first resist pattern film and thesecond resist pattern film; and removing the second resist pattern film.In this case, particularly if the second resist pattern film has a filmthickness smaller than that of the first resist pattern film, a resistpattern film equivalent to a film formed by a half exposure method inwhich the substrate surface is exposed using different light amounts canbe obtained and the thin film on the substrate can be subjected to thetwo-step patterning process. The first resist pattern film is removedafter the second resist pattern film is removed.

It is preferable that in the step of forming the second resist patternfilm, the fluid resist material is applied using an application deviceincluding a multi-nozzle injection head and a substrate stage. That is,if a plurality of the second resist pattern films is formed on thesubstrate, use of a device having, as a mechanism of injecting theresist material, a multi-nozzle injection head including many nozzles isadvantageous because a process time for one substrate can be shortened.The substrate stage is not especially limited as long as the substratecan be placed on the substrate stage. The substrate stage preferablyholds the substrate horizontally, and also preferably has a mechanism ofmoving and/or rotating the substrate.

It is preferable that the application device is an ink-jet device. Amongthem, more preferred are those in a piezo system and a bubble jet system(thermal jet system). The ink-jet device has been widely usedparticularly as a printer, and its technology has been built up.Therefore, the ink-jet device is preferably used for applying the resistmaterial at a specific position on the substrate and selectivelypreparing the second resist pattern film.

In this case, it is preferable that the fluid resist material containsat least one ether, ester, diester, and/or ether ester selected from thegroup consisting of an ethylene glycol, a diethyleneglycol, atriethyleneglycol, a polyethylene glycol, a propyleneglycol, adipropyleneglycol, a tripropylene glycol, a polypropylene glycol, and abutylene glycol, or a hydrocarbon, having a boiling point of 180° C. ormore at 1 atmosphere. Among them, preferred examples of theabove-mentioned ether, ester, diester, ether ester or hydrocarbon,having a boiling point of 180° C. or more at 1 atmosphere includetetralin (tetrahydronaphthalene), ethylene glycol, ethylene glycoldiacetate, ethylene glycol diethyl ether, ethylene glycol dibutyl ether,ethylene glycol monoacetate, ethylene glycol monoethyl ether acetate,ethylene glycol monobutyl ether acetate, ethylene glycol monohexylether, 1,3-octylene glycol, glycerol triacetate, diethylene glycol,diethylene glycol ethyl methyl ether, diethylene glycol chlorohydrin,diethylene glycol diethyl ether, diethylene glycol dibutyl ether,diethylene glycol monoethyl ether, diethylene glycol monoethyl etheracetate, diethylene glycol monobutyl ether, diethylene glycol monobutylether acetate, diethylene glycol monomethyl ether, dipropylene glycol,dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether,dipropylene glycol monopropyl ether, dipropylene glycol monomethylether, tetraethylene glycol, triethylene glycol, triethyleneglycol-di-2-ethyl butyrate, triethylene glycol dimethyl ether,triethylene glycol monoethyl ether, triethylene glycol monomethyl ether,triglycol dichloride, tripropyrene glycol, tripropylene glycolmonomethyl ether, tripropylene glycol monoethyl ether, tripropyleneglycol monobutyl ether, trimethylene glycol, 1,3-butanediol, propyleneglycol, propylene glycol phenyl ether, hexylene glycol, and1,5-pentanediol. The resist material containing such a solvent is hardlydried at near normal temperatures (20° to 30° C.) and thereforepreferably applied by the ink-jet device. If the above-mentioned ether,ester, diester, and/or ether ester, or a hydrocarbon is used as asolvent of the resist material, the resist material containing such asolvent hardly dissolves or deforms another resist pattern film which ison the substrate to which the resist material is added dropwise. This isbecause the solvent has a relatively small dissolving power for theresin.

It is preferable that the fluid resist material contains novolak resin.The above-mentioned novolak resin is widely used as a component of aphotoresist material coated on the entire surface. Also in the casewhere the coating is selectively performed as in the present invention,such a resin is used as a component, and thereby a common resist removerand a common removing process can be used. Therefore, the productionmethod of the pattern thin film according to the present invention canbe easily employed.

It is preferable that the fluid resist material contains novolak resin,and at least one ether, ester, diester, and/or ether ester selected fromthe group consisting of an ethylene glycol, a diethylene glycol, atriethylene glycol, a polyethylene glycol, a propylene glycol, adipropylene glycol, a tripropylene glycol, a polypropylene glycol, and abutylene glycol, or a hydrocarbon. These resist materials are preferablyapplied selectively on the substrate to form the resist pattern film.

The present invention is also a fluid resist material containing novolakresin and at least one ether, ester, diester, and/or ether esterselected from the group consisting of an ethylene glycol, a diethyleneglycol, a triethylene glycol, a polyethylene glycol, a propylene glycol,a dipropylene glycol, a tripropylene glycol, a polypropylene glycol, anda butylene glycol, or a hydrocarbon. These resist materials arepreferably applied selectively on the substrate to form the resistpattern film.

The present invention is a fluid resist material containing novolakresin and at least one ether, ester, diester, and/or ether esterselected from the group consisting of an ethylene glycol, a diethyleneglycol, a triethylene glycol, a polyethylene glycol, a propylene glycol,a dipropylene glycol, a tripropylene glycol, a polypropylene glycol, anda butylene glycol, or a hydrocarbon, having a boiling point of 180° C.or more at 1 atmosphere. In such a resist material of the presentinvention, examples of the above-mentioned ether, ester, diester, etherester, or hydrocarbon, having a boiling point of 180° C. or more at 1atmosphere include tetralin (tetrahydronaphthalene), ethylene glycol,ethylene glycol diacetate, ethylene glycol diethyl ether, ethyleneglycol dibutyl ether, ethylene glycol monoacetate, ethylene glycolmonoethyl ether acetate, ethylene glycol monobutyl ether acetate,ethylene glycol monohexyl ether, 1,3-octylene glycol, glyceroltriacetate, diethylene glycol, diethylene glycol ethyl methyl ether,diethylene glycol chlorohydrin, diethylene glycol diethyl ether,diethylene glycol dibutyl ether, diethylene glycol monoethyl ether,diethylene glycol monoethyl ether acetate, diethylene glycol monobutylether, diethylene glycol monobutyl ether acetate, diethylene glycolmonomethyl ether, dipropylene glycol, dipropylene glycol monoethylether, dipropylene glycol monobutyl ether, dipropylene glycol monopropylether, dipropylene glycol monomethyl ether, tetraethylene glycol,triethylene glycol, triethylene glycol-di-2-ethyl butyrate, triethyleneglycol dimethyl ether, triethylene glycol monoethyl ether, triethyleneglycol monomethyl ether, triglycol dichloride, tripropyrene glycol,tripropylene glycol monomethyl ether, tripropylene glycol monoethylether, tripropylene glycol monobutyl ether, trimethylene glycol,1,3-butanediol, propylene glycol, propylene glycol phenyl ether,hexylene glycol, and 1,5-pentanediol. These resist materials arepreferably applied selectively on the substrate to form the resistpattern film.

The present invention is also a production method of a semiconductorelement, wherein a semiconductor layer, a source electrode, and a drainelectrode are formed by patterning a semiconductor film and a metal filmformed on a substrate, using the above-mentioned production method ofthe pattern thin film (hereinafter, also referred to as first productionmethod of a semiconductor element). According to the first productionmethod of the semiconductor element of the present invention, asemiconductor layer, a source electrode, and a drain electrode can beformed from a semiconductor film and a metal film using the productionmethod of the pattern film according to the present invention.Therefore, environmental loads, material costs, and equipment investmentcosts in production of a semiconductor element such as a thin filmtransistor can be reduced.

For example, a thin film transistor is formed through a step of forminga semiconductor film and a metal film on a substrate, a step of forminga first resist pattern film on the metal film, a step of applying afluid resist material on a groove of a bank pattern formed using thefirst resist film, thereby forming a second resist pattern film. As aresult, a thin film transistor, in which a source electrode and a drainelectrode formed by processing the metal film into a shape of the firstresist pattern film and a semiconductor layer formed by processing thesemiconductor film into a combination shape of the first resist patternfilm with the second resist pattern film are included and a channelregion of the thin film transistor is formed at a position where thesecond resist pattern film, is formed. In such a thin film transistor,if the first resist pattern film is prepared by photolithographytechnique, for example, the source electrode and the drain electrode,and the channel region are generally prepared through onephotolithography process and a step of applying the resist material onthe substrate. Conventionally, the process for the metal film and theprocess for the semiconductor layer are performed separately throughdifferent photolithography processes. Therefore, in comparison to such aconventional method, one photolithography process is omitted, and oneeach of the exposure steps and the development steps using a photomaskis omitted. Therefore, the environmental loads, the material costs, andthe equipment investment costs in the production of the thin filmtransistor can be reduced.

The present invention is also a production method of a semiconductorelement having a channel, including a step of forming a resist patternfilm on a thin film formed on a substrate and pattering the thin film byetching,

wherein the production method includes a step of forming a second resistpattern film by applying a fluid resist material inside a channel grooveafter channel etching or inside a resist groove formed above a channelregion before channel etching (hereinafter, also referred to as secondproduction method of the semiconductor element).

The above-mentioned channel etching is not especially limited as long asit is an etching for forming the channel groove. Such a channel etchingmay be a wet etching or a dry etching, and a wet etching is preferablein view of reduction in production costs.

The above-mentioned channel groove means a groove which is constitutedby a bank including essential components constituting the semiconductorelement and formed at the channel region. The embodiment of the channelgroove is not especially limited, and examples thereof include a grooveformed between the source electrode and the drain electrode; and agroove formed between a multilayer film of the source electrode and theresist pattern film, and a multilayer film of the drain electrode andthe resist pattern film. If the semiconductor layer is a stacked bodyincluding an upper semiconductor layer and a lower semiconductor layer,examples of the channel groove include: a groove formed between amultilayer film including an upper semiconductor layer on the sourceside and the source electrode, and a multilayer film including an uppersemiconductor layer on the drain side and the drain electrode; and agroove formed between a multilayer film including an upper semiconductorlayer on the source side, the source electrode, and the resist patternfilm, and a multilayer film including an upper semiconductor layer ondrain side, the drain electrode, and the resist pattern film.

That is, the resist pattern film used as a mask in the channel etchingmay be removed before application of the fluid resist material, or maybe left. The above-mentioned resist groove means a groove which isconstituted by the resist pattern film and formed at the channel region.

The size of the above-mentioned channel groove and resist groove isgenerally determined in such a way that the semiconductor element showsspecific performances when used as a product, and also determined inview of a droplet amount of the resist material to be applied and otherset production conditions. If the semiconductor element is a TFT in aTFT array substrate used in a display device, as one example, it ispreferable that the size of the channel groove and the resist groove hasa length of 5 μm or more and 100 μm or less, and a width of 1 μm or moreand 10 μm or less, and a depth of 0.01 μm or more and 10 μm or less. Theabove-mentioned length of the channel groove and the resist groove meansa length in the extending direction of the channel groove and the resistgroove. The above-mentioned width of the channel groove and the resistgroove means a distance between the source electrode and the drainelectrode.

The number of the channel groove and the resist groove may be one or twoor more in each semiconductor element.

According to the second production method of the semiconductor elementof the present invention, one each of the photolithography process andthe selective application of the resist material is performed, andthereby the two-step patterning process can be performed. According tothis production method, the channel groove or the resist groove functionas a groove of the bank pattern for controlling the shape of thedroplet, and therefore variation in shape of the resist pattern films isreduced. As a result, variation in characteristics among thesemiconductor elements can be reduced.

Preferred embodiments of the second production method of thesemiconductor element according to the present invention include anembodiment in which the production method of the semiconductor elementincludes the steps of: including the steps of: successively forming agate electrode, a gate insulating film, a semiconductor film, and aconductive film on an insulating substrate; forming a first resistpattern film having the resist groove on the conductive film; patterningthe conductive film using the first resist pattern film, thereby formingthe channel groove; applying the fluid resist material inside thechannel groove, thereby forming the second resist pattern film; andpatterning the semiconductor film using at least the second resistpattern film (hereinafter, also referred to as “first embodiment”).According to this, one each of the photolithography process for channeletching and the selective application of the resist material isperformed, and thereby the two-step patterning process can be performed.That is, through the patterning process using the photolithography atthe first step, the source electrode and the drain electrode are formedfrom the conductive film. Further, through the patterning process usingselective application of the resist material at the second step, thesemiconductor layer is formed from the semiconductor film. Accordingly,through two photolithography processes including formation of the gateelectrode, a basic structure of an inverse stagger type semiconductorelement can be formed. The semiconductor layer is formed by removing thesemiconductor film in the first resist pattern film-formed region(source electrode and drain electrode-formed region) and a region otherthan the second resist pattern film-formed region by etching. At thistime, if the source electrode and the drain electrode have resistancefor etching of the semiconductor film, it can be possible to perform theetching after the first resist pattern film is removed. In this case,the second resist pattern film, the source electrode, and the drainelectrode are used as a mask.

According to the above-mentioned first embodiment, it is preferable thatthe semiconductor film includes an upper semiconductor film and a lowersemiconductor film; the channel groove is formed by patterning theconductive film and the upper semiconductor film using the first resistpattern film; and the lower semiconductor film is patterned using atleast the second resist pattern film. That is, the preferableembodiments of the second production method of the semiconductor elementaccording to the present invention include an embodiment in which theproduction method of the semiconductor element, includes the steps of:including the steps of: successively forming a gate electrode, a gateinsulating film, a lower semiconductor film, an upper semiconductorfilm, and a conductive film on an insulating substrate; forming a firstresist pattern film having the resist groove on the conductive film;patterning the conductive film and the upper semiconductor film usingthe first resist pattern film, thereby forming the channel groove;applying the fluid resist material inside the channel groove, therebyforming the second resist pattern film; and patterning the lowersemiconductor film using at least the second resist pattern film.According to this, through one each of the photolithography process forchannel etching and the selective application of the resist material,the two-step patterning process can be performed. That is, through thepatterning process using the photolithography process at the first step,the source electrode and the drain electrode are formed from theconductive film, and an upper semiconductor layer on the source side andan upper semiconductor layer on the drain side are formed from the uppersemiconductor film. Further, through the patterning process usingselective application of the resist material at the second step, a lowersemiconductor layer is formed from the lower semiconductor film.Accordingly, through two photolithography processes including formationof the gate electrode, a basic structure of an inverse stagger typesemiconductor element can be formed. The lower semiconductor layer isformed by removing the lower semiconductor film in the firstresist-pattern film-formed region (source electrode and drainelectrode-formed region) and a region other than the second resistpattern film-formed region by etching. At this time, if the sourceelectrode and the drain electrode have resistance for etching of thelower semiconductor film, it can be possible to perform the etchingafter the first resist pattern film is removed. In this case, the secondresist pattern film, the source electrode, and the drain electrode areused as a mask.

Preferable embodiments of the second production method of thesemiconductor element according to the present invention include anembodiment in which the production method of the semiconductor elementincludes the steps of: successively forming a gate electrode, a gateinsulating film, a semiconductor film, and a conductive film on aninsulating substrate; forming a first resist pattern film having theresist groove on the conductive film; applying the fluid resist materialinside the resist groove, thereby forming the second resist patternfilm; patterning the semiconductor film and the conductive film usingthe first and second resist pattern films; removing the second resistpattern film; and patterning the conductive film using the first resistpattern film after removal of the second resist pattern film(hereinafter, also referred to as “second embodiment”). According tothis, using the first and second resist pattern films, a resist patternfilm having portions with different film thicknesses (halftone pattern)is formed on the multilayer film, and the two step-patterning processcan be performed. That is, through the patterning process at the firststep, the semiconductor film and the conductive film are patterned, andthereby the semiconductor layer can be formed from the semiconductorfilm. Further, through the patterning process at the second step afterthe selective removal of the second resist pattern film, the conductivefilm is further processed to form the source electrode and the drainelectrode. Accordingly, through two photolithography processes includingformation of the gate electrode, a basic structure of an inverse staggertype semiconductor element can be formed. The step of removing thesecond resist pattern film may serve as a step of thinning the firstresist pattern film. If the second resist pattern film has a thicknesssmaller than that of the first resist pattern film, for example, thesecond resist pattern film can be selectively removed by thinning thefirst and second resist pattern films.

According to the above-mentioned second embodiment, it is preferablethat the semiconductor film includes an upper semiconductor film and alower semiconductor film; and after removal of the second resist patternfilm, the conductive film and the upper semiconductor film are patternedusing the first resist pattern film. That is, the preferable embodimentsof the production method of the second semiconductor element accordingto the present invention includes the steps of: successively forming agate electrode, a gate insulating film, a lower semiconductor film, anupper semiconductor film, and a conductive film on an insulatingsubstrate; forming a first resist pattern film having the resist grooveon the conductive film; applying the fluid resist material inside theresist groove, thereby forming the second resist pattern film having afilm thickness smaller than that of the first resist pattern film;patterning the lower semiconductor film, the upper semiconductor film,and the conductive film using the first and second resist pattern films;removing the second resist pattern film by thinning the first and secondresist pattern films; and patterning the upper semiconductor film andthe conductive film using the thinned first resist pattern film.According to this, using the first and second resist pattern films, aresist pattern film with portions having different film thicknesses(halftone pattern) is formed on the multilayer film, and the two-steppatterning process can be performed. That is, through the patterningprocess at the first step, the lower semiconductor layer, the uppersemiconductor layer, and the conductive film are patterned, and therebythe lower semiconductor layer can be formed from the lower semiconductorfilm. Further, through the patterning process at the second step afterthe selective removal of the second resist pattern film, the conductivefilm is further processed to form the source electrode and the drainelectrode, and the upper semiconductor film is further processed to forman upper semiconductor layer on the source side and an uppersemiconductor layer on the drain side. Accordingly, through twophotolithography processes including formation of the gate electrode, abasic structure of an inverse stagger type semiconductor element can beformed.

If the above-mentioned halftone pattern is formed, it is preferable thatthe film thickness of the second resist pattern film accounts for 50% orless of that of the first resist pattern film. It is also preferablethat the second resist pattern film has a film thickness of 1000 Å ormore. The first resist pattern film may be a resist having a lyophobicproperty for the fluid resist material (lyophobic resist) in view ofreduction in addition accuracy of the fluid resist material.

The present invention is also a production method of a semiconductorelement having a channel, including a step of forming a resist patternfilm on a thin film formed on a substrate and pattering the thin film byetching, wherein the production method includes a step of addingdropwise a solvent inside a channel groove formed above a channel regionafter channel etching using a first resist pattern film, or inside aresist groove formed from the first resist pattern film above thechannel region before channel etching to dissolve the first resistpattern film around the channel groove or the resist groove, therebyforming a second resist pattern film (hereinafter, also referred to asthird production method of the semiconductor element).

The size of the above-mentioned channel groove and resist groove isgenerally determined in such a way that the semiconductor element showsspecific performances when used as a product, and also determined inview of a droplet amount of the resist material to be applied and otherset production conditions. If the semiconductor element is a TFT in aTFT array substrate used in a display device, as one example, it ispreferable that the size of the channel groove and the resist groove hasa length of 5 μm or more and 100 μm or less, and a width of 1 μm or moreand 10 μm or less, and a depth of 0.01 μm or more and 10 μm or less. Theabove-mentioned length of the channel groove and the resist groove meansa length in the extending direction of the channel groove and the resistgroove. The above-mentioned width of the channel groove and the resistgroove means a distance between the source electrode and the drainelectrode. The number of the channel groove and the resist groove may beone or two or more in each semiconductor element. A solvent capable ofdissolving the first resist pattern film is appropriately selected andused as the solvent added dropwise into the channel groove and theresist groove. Examples of organic solvents include: hydrocarbons suchas decalin (decahydronaphthalene) and decane; alcohols such as ethanol,methanol, and isopropyl alcohol; ketones such as acetone, methylisobutyl ketone, and methyl ethyl ketone; and esters such as butylacetate, ethyl acetate, butyl lactate, and ethyl lactate. Among them,preferably used are organic solvents having a boiling point of 180° C.or more, such as tetralin (tetrahydronaphthalene), ethylene glycol,ethylene glycol diacetate, ethylene glycol diethyl ether, ethyleneglycol dibutyl ether, ethylene glycol monoacetate, ethylene glycolmonoethyl ether acetate, ethylene glycol monobutyl ether acetate,ethylene glycol monohexyl ether, 1,3-octylene glycol, glyceroltriacetate, diethylene glycol, diethylene glycol ethyl methyl ether,diethylene glycol chlorohydrin, diethylene glycol diethyl ether,diethylene glycol dibutyl ether, diethylene glycol monoethyl ether,diethylene glycol monoethyl ether acetate, diethylene glycol monobutylether, diethylene glycol monobutyl ether acetate, diethylene glycolmonomethyl ether, dipropylene glycol, dipropylene glycol monoethylether, dipropylene glycol monobutyl ether, dipropylene glycol monopropylether, dipropylene glycol monomethyl ether, tetraethylene glycol,triethylene glycol, triethylene glycol di-2-ethyl butyrate, triethyleneglycol dimethyl ether, triethylene glycol monoethyl ether, triethyleneglycol monomethyl ether, triglycol dichloride, tripropyrene glycol,tripropylene glycol monomethyl ether, tripropylene glycol monoethylether, tripropylene glycol monobutyl ether, trimethylene glycol,1,3-butanediol, propylene glycol, propylene glycol phenyl ether,hexylene glycol, and 1,5-pentanediol. Such a solvent is hardly dried atnear normal temperatures (20° to 30° C.) and therefore preferablyapplied by the ink-jet device.

According to such a third production method of the semiconductor elementof the present invention, one each of the photolithography process andthe selective application of the solvent is performed, and thereby thetwo-step patterning process can be performed. According to thisproduction method, the channel groove or the resist groove function as agroove of the bank pattern for controlling the shape of the droplet, andtherefore variation in the shape of the resist pattern film is reduced.As a result, variation in characteristics among the semiconductorelements can be reduced.

Preferable embodiments of the third production method of thesemiconductor element include an embodiment in which the productionmethod of the semiconductor element includes the steps: successivelyforming a gate electrode, a gate insulating film, a semiconductor film,and a conductive film on an insulating substrate; forming a first resistpattern film having the resist groove on the conductive film; patterningthe conductive film using the first resist pattern film, thereby formingthe channel groove; adding dropwise the solvent inside the channelgroove to dissolve the first resist pattern film around the channelgroove, thereby forming the second resist pattern film; and patterningthe semiconductor film using the first and second resist pattern films(hereinafter, also referred to as “third embodiment”). According tothis, one each of the photolithography process for channel etching andthe selective application of the solvent is performed, and thereby thetwo-step patterning process can be performed. That is, through thepatterning process using the photolithography at the first step, thesource electrode and the drain electrode are formed from the conductivefilm. Further, through the patterning process using the selectiveapplication of the solvent at the second step, the semiconductor layercan be formed from the semiconductor film. Accordingly, through twophotolithography processes including formation of the gate electrode, abasic structure of an inverse stagger type semiconductor element can beformed. The lower semiconductor layer is formed by removing thesemiconductor film in the first resist pattern film-formed region(source electrode and drain electrode-formed region) and a region otherthan the second resist pattern film-formed region by etching.

In the above-mentioned third embodiment, it is preferable that thesemiconductor film includes an upper semiconductor film and a lowersemiconductor film; the channel groove is formed by patterning theconductive film and the upper semiconductor film using the first resistpattern film; and the lower semiconductor film is patterned using thefirst and second resist pattern films. That is, the preferableembodiments of the third production method of the semiconductor elementaccording to the present invention include the production method of thesemiconductor element, includes the steps of: successively forming agate electrode, a gate insulating film, a lower semiconductor film, anupper semiconductor film, and a conductive film on an insulatingsubstrate; forming a first resist pattern film having the resist grooveon the conductive film; patterning the conductive film and the uppersemiconductor film using the first resist pattern film, thereby formingthe channel groove; adding dropwise the solvent inside the channelgroove to dissolve the first resist pattern film around the addedsolvent, thereby forming the second resist pattern film; and patterningthe lower semiconductor film using the first and second resist patternfilms. According to this, one each of the photolithography process forchannel etching and the selective application of the solvent isperformed, and thereby the two-step patterning process can be performed.That is, through the patterning process using the photolithographyprocess at the first step, the source electrode and the drain electrodeare formed from the conductive film, and an upper semiconductor layer onthe source side and an upper semiconductor layer on the drain side areformed from the upper semiconductor film. Further, through thepatterning process using the selective application of the solvent at thesecond step, a lower semiconductor layer is formed from the lowersemiconductor film. Accordingly, through two photolithography processesincluding formation of the gate electrode, a basic structure of aninverse stagger type semiconductor element can be formed. The lowersemiconductor layer is formed by removing the lower semiconductor filmin the first resist pattern film-formed region (source electrode anddrain electrode-formed region) and a region other than the second resistpattern film-formed region by etching.

Preferable embodiments of the third production method of thesemiconductor element according to the present invention include anembodiment in which the production method of the semiconductor elementincludes the steps of: successively forming a gate electrode, a gateinsulating film, a semiconductor film, and a conductive film on aninsulating substrate; forming the first resist pattern film having theresist groove on the conductive film; adding dropwise the solvent insidethe resist groove to dissolve the first resist pattern film around theresist groove, thereby forming the second resist pattern film;patterning the semiconductor film and the conductive film using thefirst and second resist pattern films; removing the second resistpattern film; after removal of the second resist pattern film,patterning the conductive film using the first resist pattern film(hereinafter, also referred to as “fourth embodiment”). According tothis, using the first and second resist pattern films, a resist patternfilm with portions having different film thicknesses (halftone pattern)is formed on the multilayer film, and thereby the two-step patterningprocess can be performed. That is, through the patterning process at thefirst step, the semiconductor film and the conductive film arepatterned, and the semiconductor layer is formed from the semiconductorfilm. Further, through the patterning process at the second step afterthe selective removal of the second resist pattern film, the conductivefilm is further processed to form the source electrode and the drainelectrode. Accordingly, through two photolithography processes includingformation of the gate electrode, a basic structure of an inverse staggertype semiconductor element can be formed.

According to the above-mentioned fourth embodiment, it is preferablethat the semiconductor film includes an upper semiconductor film and alower semiconductor film; and after removal of the second resist patternfilm, the conductive film and the upper semiconductor film are patternedusing the first resist pattern film. That is, the preferable embodimentsof the third production method of the semiconductor element include anembodiment in which the production method of the semiconductor elementincludes the steps of: successively forming a gate electrode, a gateinsulating film, a lower semiconductor film, an upper semiconductorfilm, and a conductive film on an insulating substrate; forming thefirst resist pattern film having the resist groove on the conductivefilm; adding dropwise the solvent inside the resist groove to dissolvethe first resist pattern film around the added solvent, thereby formingthe second resist pattern film; patterning the lower semiconductor film,the upper semiconductor film, and the conductive film using the firstand second resist pattern films; removing the second resist patternfilm; after removal of the second resist pattern film, patterning theconductive film and the upper semiconductor film using the first resistpattern film. According to this, using the first and second resistpattern films, a resist pattern film having portions with different filmthicknesses (halftone pattern) is formed on the multilayer film, andthereby the two-step patterning process can be performed. That is,through the patterning process at the first step, the lowersemiconductor film, the upper semiconductor film, and the conductivefilm are patterned, and the lower semiconductor layer is formed from thesemiconductor film. Further, through the patterning process at thesecond step after the selective removal of the second resist patternfilm, the conductive film is further processed to form the sourceelectrode and the drain electrode, and the upper semiconductor film isfurther processed to form an upper semiconductor layer on the sourceside and an upper semiconductor layer on the drain side. Accordingly,through two photolithography processes including formation of the gateelectrode, a basic structure of an inverse stagger type semiconductorelement can be formed.

It is preferable that the second and third production methods of thesemiconductor element according to the present invention each include astep of bonding a fluorine atom and/or a fluorine compound to a surfaceof the substrate, before the step of forming the second resist patternfilm. If at least the periphery of the channel groove or the resistgroove on the substrate surface is provided with a lyophobic propertyfor the fluid resist material or the solvent, spread (size) of thedroplet of the resist material or the solvent immediately after landedcan be controlled and variation in characteristics among the elementscan be effectively reduced. It is preferable that the above-mentionedfluorine-bonding step is performed just before dropwise addition of thefluid resist material or the solvent. A plasma surface treatment such asfluorine plasma treatment is preferably used, for example, as a methodof the above-mentioned fluorine bonding.

It is preferable that the fluid resist material or the solvent is addeddropwise with an ink-jet device. Material costs and the like can bereduced, which more improves productivity. In addition, the ink-jetdevice is preferable because a droplet as small as several pl can beadded dropwise, and therefore the fluid resist material or the solventcan be selectively injected into the channel groove or the resist groovewith several to several tens of micrometers.

If a plurality of channel grooves or resist grooves is arrayed in amatrix pattern and a distance between adjacent channel grooves or resistgrooves in the horizontal direction is smaller than that in the verticaldirection, it is preferable that the ink-jet head is moved in thehorizontal direction in view of easiness of nozzle process and reductionin process time.

It is preferable that the resist material has a viscosity of 5 cP ormore and 30 cP or less. Within this viscosity range, such a resistmaterial is suitably applied with the ink-jet device, and the dropwiseaddition from the ink-jet head can be stabilized. The viscosity of theresist material tends to increase with increase in solid contents in theresist material, and therefore it is preferable that the concentrationof the solid contents is adjusted in such a way that the material has adesired viscosity.

Further, the addition amount per injection is preferably 0.5 pl or moreand 10 pl or less if a TFT in a TFT array-substrate used in a displaydevice is produced, although it depends on the shape of the channelgroove or the resist groove, the size thereof, and the like.

The present invention is a production method of a circuit substrate,wherein a semiconductor element is formed on a substrate using the firstto third production method of the semiconductor element according to thepresent invention. A thin film transistor (TFT), a thin film diode, andthe like may be mentioned as the above-mentioned semiconductor element.The above-mentioned circuit substrate is not especially limited as longas it has a circuit including a semiconductor element on a substrate,and a TFT array substrate and the like may be mentioned. According tothe production method of the circuit substrate of the present invention,one photolithography process can be omitted, and therefore environmentalloads, material costs, equipment investment costs in the production ofthe production of the circuit substrate can be reduced.

In the production method of the circuit substrate of the presentinvention, it is preferable that the circuit substrate constitutes adisplay device or an imaging device; a semiconductor element in adisplay region or an imaging region and a semiconductor element in anon-display region or a non-imaging region are disposed on a group ofparallel lines extending in an extending direction of a gate wiringand/or a source wiring; and in the step of forming the second resistpattern film, a fluid resist material or a solvent is applied bycontinuously moving an injection head or a substrate stage in theextending direction of the gate wiring and/or the source wiring in thedisplay region or the imaging region and the non-display region or thenon-imaging region. According to such a method, using the productionmethod of the semiconductor element of the present invention, the resistmaterial or the solvent is added dropwise by scanning the injection headin the extending direction of the gate wiring and/or the source wiring.As a result, the semiconductor element in the display region and thesemiconductor element in the non-display region can be simultaneouslyprepared in production of the circuit substrate constituting a displaydevice, and the semiconductor element in the imaging region and thesemiconductor element in the non-imaging region can be simultaneouslyprepared in production of the circuit substrate constituting an imagingdevice. Therefore, environmental loads, material costs, and equipmentinvestment costs in the production of the circuit substrate can bereduced, and the process time also can be shortened. The above-mentioneddisplay region or imaging region is generally positioned in the centerof the circuit substrate, and for example, a TFT as a switching forvoltage application to a pixel electrode is positioned in each pixel.The above-mentioned non-display region or non-imaging region isgenerally positioned in the periphery (frame part) of the circuitsubstrate, and in such a region, a thin film diode for preventingelectrostatic breakdown of the TFT formed in the display region or theimaging region and/or the wiring, a TFT for a driving circuit, and thelike, are disposed, for example. The above-mentioned circuit substratemay have a configuration in which the semiconductor element in thedisplay region or the imaging region and the semiconductor element inthe non-display region or the non-imaging region are disposed on acommon group of parallel lines extending in the extending direction ofthe gate wiring and/or the source wiring, and simultaneously have aconfiguration in which a semiconductor element is disposed on anothergroup of parallel lines extending in the extending direction of the gatewiring and/or the source wiring. In the above-mentioned circuitsubstrate, other semiconductor elements may be disposed, in addition tothe semiconductor element formed on the group of parallel linesextending in the extending direction of the gate wiring or the sourcewiring.

In this case, it is preferable that the above-mentioned injection headis continuously moved in the extending direction of the gate wiring. Inthe circuit substrate such as a TFT array substrate, a plurality of gatewirings and source wirings is disposed to be perpendicular to eachother, and the distance between adjacent gate wirings (gate wiringpitch) is generally larger than that between adjacent source wirings(source wiring pitch). Therefore, the second resist pattern film issuccessively applied and formed in the gate wiring direction, andthereby the number of the nozzle machinery formed in the injection headcan be reduced. Therefore, the injection head is easily prepared, whichleads to reduction in equipment investment costs.

The present invention is also a semiconductor element including asemiconductor layer on a substrate side of a source electrode and adrain electrode, the semiconductor layer being disposed at a spacebetween the source electrode and the drain electrode to form a channeland further being disposed on a substrate side of a source wiringconnected to the source electrode, wherein the channel of thesemiconductor element has a curved end between the source electrode andthe drain electrode (hereinafter, also referred to as firstsemiconductor element) The first semiconductor element according to thepresent invention has the same characteristics as in the semiconductorelement in which the resist pattern film at the channel is formed of afluid resist material, and can be produced by the first to thirdproduction method of the semiconductor element in the present invention.That is, if the resist pattern film at the channel is formed by addingthe fluid resist material or the solvent between the source electrodeand the drain electrode using such electrodes as a bank, the resistmaterial or the solvent added dropwise between the source electrode andthe drain electrode has a curved shape because of its surface tension.Accordingly, if the resist material or the solvent is used to form theresist pattern film at the channel, the obtained semiconductor elementhas a curve-shaped channel end positioned between the source electrodeand the drain electrode. Examples of the curve-shape of the end of thefunctional layer include an ellipse shape projecting in the enddirection and an ellipse shape projecting in the direction opposed tothe end. In the first semiconductor element of the present invention,the element structure can be formed through a smaller number ofphotolithography processes. Therefore, environmental loads, materialcosts, and equipment investment costs in the production of thesemiconductor element can be reduced. If the semiconductor element isformed by the first to third production method of the semiconductorelement according to the present invention, the source wiring connectedto the source electrode of the semiconductor element also has asemiconductor layer on the substrate side. Such a semiconductor elementgenerally has an embodiment in which the semiconductor layer is formedover the entire surface on the substrate side of the source wiringconnected to the source electrode.

The number of the above-mentioned channel of the semiconductor elementis not especially limited and may be one or two or more in eachsemiconductor element.

The present invention is also a semiconductor element including asemiconductor layer on a substrate side of a source electrode and adrain electrode, the semiconductor layer being disposed at a spacebetween the source electrode and the drain electrode to form a channeland further being disposed on a substrate side of a source wiringconnected to the source electrode, wherein at least one of the sourceelectrode and the drain electrode has a notch at an end on a channelside (hereinafter, also refer to second semiconductor element). Thesecond semiconductor element of the present invention has a structureadvantageous for the case where the resist pattern film at the channelis formed of a fluid material. That is, if at least one of the sourceelectrode and the drain electrode has a notch at the end on the channelside (facing the channel), the channel groove or the resist groove havea liquid-saving part and thereby its capacity can be increased. As aresult, it becomes easier for the fluid material added dropwise into thechannel groove or the resist groove to be kept inside the groove, andthereby the resist pattern film can be formed with accuracy. The secondsemiconductor element of the present invention is preferably produced bythe first to third production method of the semiconductor element of thepresent invention. Such a semiconductor element has an embodiment inwhich the semiconductor layer is formed over the entire surface on thesubstrate side of the source wiring connected to the source electrode.The above-mentioned notch is not especially limited as long as it canenlarge the channel groove or the resist groove. The shape of the notchis not especially limited, and examples thereof include a triangle, asquare, and a semicircle. The number of the notch is not especiallylimited and may be one or two or more in each semiconductor element.

The present invention is also a semiconductor element including asemiconductor layer on a substrate side of a source electrode and adrain electrode, the semiconductor layer being disposed at a spacebetween the source electrode and the drain electrode to form a channeland further being disposed on a substrate side of a source wiringconnected to the source electrode, wherein the semiconductor element hasa dummy channel near the channel (hereinafter, also referred to as thirdsemiconductor element). The third semiconductor element of the presentinvention has a structure advantageous for the case where the resistpattern film at the channel is formed of a fluid material. That is, ifthe semiconductor element has a dummy channel near the channel, aliquid-saving part can be formed near the channel groove or the resistgroove. As a result, the fluid material added dropwise into the channelgroove or the resist groove is kept also at the liquid-saving part andthereby easily kept inside the groove. Therefore, the resist patternfilm can be formed with accuracy.

The third semiconductor element of the present invention is preferablyproduced by the first to third production method of the semiconductorelement of the present invention. Such a semiconductor element generallyhas an embodiment in which the semiconductor layer is formed on theentire surface on the substrate side of the source wiring connected tothe source electrode.

The above-mentioned dummy channel is not especially limited as long asit is a region formed on the semiconductor layer by a notch of thesource electrode and/or the drain electrode and functions as theliquid-saving part. It is preferable that the dummy channel is disposedwithin 20 μm from the channel in order to more effectively function asthe liquid-saving part. The shape of the dummy channel is not especiallylimited. The number of the dummy channel is not especially limited andmay be one or two or more in each semiconductor element.

The present invention is also a semiconductor element including asemiconductor layer on a substrate side of a source electrode and adrain electrode, the semiconductor layer being disposed at a spacebetween the source electrode and the drain electrode to form a channeland further being disposed on a substrate side of a source wiringconnected to the source electrode, wherein the semiconductor element hasa dummy electrode between the source electrode and the drain electrode(hereinafter, also referred to as fourth semiconductor element). Thefourth semiconductor element of the present invention has a structureadvantageous for the case where the resist pattern film at the channelis formed of a fluid material. That is, if the channel groove or theresist groove has a width that is too large for the size of the landeddroplet of the fluid material added into the groove, a dummy electrodeis formed between the source electrode and the drain electrode to dividethe channel groove or the resist groove into plural portions, andthereby, the fluid material added dropwise into the groove can bedivided and kept. As a result, the fluid material added dropwise intothe groove can be easily kept inside the groove and the resist patternfilm can be formed with accuracy. The fourth semiconductor element ofthe present invention is preferably produced by the first to thirdproduction method of the semiconductor element of the present invention.Such a semiconductor element generally has an embodiment in which thesemiconductor layer is formed on the entire surface on the substrateside of the source wiring connected to the source electrode.

The above-mentioned dummy electrode is not especially limited as long asit is effective for controlling the shape of the droplet added betweenthe source electrode and the drain electrode and it is a structureformed separately from other electrodes. However, it is more preferablethat the dummy channel is disposed within 20 μm from the sourceelectrode and the drain electrode in order to more effectively functionas the liquid-saving part. The material for the dummy electrode is notespecially limited, and is preferably the same as that for the sourceelectrode and the drain electrode. In this case, the dummy electrode canbe simultaneously prepared in the step of forming the source electrodeand the drain electrode. The shape of the dummy electrode is notespecially limited. The number of the dummy electrode is not especiallylimited and may be one or two or more in each semiconductor element.

The preferable embodiments of the second to fourth semiconductorelements of the present invention include an embodiment in which thechannel has a flared part on the source electrode side and/or the drainelectrode side; an embodiment in which the channel has a flared partoutward; an embodiment in which at least one of the source electrode andthe drain electrode has two or more comb-shaped parts (notches) andbetween such comb-shaped parts, the dummy channel is formed; anembodiment in which at least one of the source electrode and the drainelectrode has a structure divided into two or more portions by a notch,and between the divided portions, the dummy channel is formed; anembodiment in which the semiconductor element has a dummy electrode, andthe dummy channel is formed between the source electrode and the dummyelectrode, between the drain electrode and the dummy electrode, and/orbetween the dummy electrode and the dummy channel. Among them, anembodiment in which the notch has a linewidth equivalent to the channellength of the semiconductor element (TFT) is preferably employed.

The present invention is also a semiconductor element including asemiconductor layer on a substrate side of a source electrode and adrain electrode, the semiconductor layer being disposed at a spacebetween the source electrode and the drain electrode to form a channel,and further being disposed on a substrate side of a source wiringconnected to the source electrode, wherein the channel of thesemiconductor element has a shape with two or more bent portions(hereinafter, also referred to as fifth semiconductor element). Thefifth semiconductor element of the present invention has a structureadvantageous for the case where the resist pattern film at the channelis formed of a fluid material. That is, if the channel of thesemiconductor element is bent at two or more points, the entire channelcan be within a smaller circle even if the whole length of the channelis the same. Therefore, the resist pattern film can be easily formed byaddition of the droplet. In addition, a proportion of the channel areato the area of the portion where the semiconductor element is formed inthe semiconductor layer can be increased, and therefore the capacity ofthe channel groove or the resist groove can be increased. As a result,the fluid material added dropwise into the channel groove or the resistgroove can be easily kept inside the groove, and therefore the resistpattern film can be formed with accuracy. The fifth semiconductorelement of the present invention can be preferably produced by the firstto third production method of the semiconductor element of the presentinvention. Such a semiconductor element generally has an embodiment inwhich the semiconductor layer is formed on the entire surface on thesubstrate side of the source wiring connected to the source electrode.The bent portion of the channel may be a portion bent at a right angleor may be a curved portion.

The more preferable embodiments of the fifth semiconductor element ofthe present invention include an embodiment in which the channel has asquare U-shape; an embodiment in which the channel has a U-shape; and anembodiment in which the channel has a Z shape. It is particularlypreferable that the channel has a square U-shape or a U-shape.

The present invention is a semiconductor element including asemiconductor layer on a substrate side of a source electrode and adrain electrode, the semiconductor layer being disposed at a spacebetween the source electrode and the drain electrode to form a channel,and further being disposed on a substrate side of a source wiringconnected to the source electrode, wherein the source electrode and thedrain electrode have corners on both sides of ends of the channel(hereinafter, also referred to as sixth semiconductor element). Thesixth semiconductor element of the present invention has a structureadvantageous for the case where the resist pattern film at the channelis formed of a fluid material. If the end of the channel groove or theresist groove is formed at a portion where the corner of the sourceelectrode and that of the drain electrode are disposed to face eachother, the fluid material can be suppressed from being wetly spread tothe outside of the channel groove or the resist groove along the bankpositioned at both sides of the channel groove or the resist groove. Asa result, the fluid material added dropwise into the channel groove orthe resist groove can be easily kept inside the groove, and thereforethe resist pattern film can be formed with accuracy. That is, the resistpattern film can be formed with accuracy by the first to thirdproduction method of the semiconductor element of the present invention,if the semiconductor element having an embodiment in which the sourceelectrode and the drain electrode have corners on both sides of ends ofthe channel (the end of the channel is positioned at the portion wherethe corner of the source electrode and the corner of the drain electrodeare disposed to face to each other). The sixth semiconductor element ofthe present invention is preferably produced by the first to thirdproduction method of the semiconductor element of the present invention.Such a semiconductor element generally has an embodiment in which thesemiconductor layer is formed on the entire surface on the substrateside of the source wiring connected to the source electrode.

In the sixth semiconductor element of the present invention, a contourof the above-mentioned corner of the source electrode and the drainelectrode may have a shape formed with a curved line, but preferably hasa shape formed with two straight lines. The angle of the corner of thesource electrode and the drain electrode is preferably 135° or less, andmore preferably 90° or less, and still more preferably 90°. If the dummychannel is formed, it is preferable that the source electrode and thedrain electrode have corners on both sides of ends of the dummy channel.

The semiconductor element of the present invention has any of the firstto sixth semiconductor elements, or an embodiment in which suchembodiments are combined.

If the fluid material may possibly flow out of the channel groove or theresist groove when the semiconductor element of the present invention isproduced, it is preferable that a treatment for determining thedirection where the fluid material flows is previously performed.Specifically, a method of controlling the shape of the source electrodeand the drain electrode, the conditions of the addition of the fluidmaterial, and the like, may be mentioned. For example, if a capacity(Cg-d) between the gate electrode and the drain electrode varies in aTFT in a TFT array substrate used in a liquid crystal display device,influence on display quality becomes larger in comparison to the casewhere a capacity (Cg-d) between the gate electrode and the sourceelectrode varies. Therefore, it is better that the treatment isperformed in such a way that the fluid material flows to the sourceelectrode side.

It is preferable that the semiconductor element of the present inventionis a thin film transistor (TFT) or a thin film diode (TFD). Thepreferable embodiments of the TFT or TFD include an embodiment in whicha gate electrode, a gate insulating layer, and a semiconductor layer aresuccessively formed on an insulating substrate, and on the semiconductorlayer, a source electrode is stacked via a contact layer on the sourceelectrode side, and a drain electrode is stacked via a contact layer onthe drain electrode side. Such a TFT or TFD is used as an inversestagger type. In the present invention, the TFD is generally formed byelectrically connecting the gate electrode to the source electrode, orconnecting the gate electrode to the drain electrode.

The present invention is also a circuit substrate including asemiconductor element produced by the first to third production methodof the semiconductor element according to the present invention, orincluding the first to sixth semiconductor element according to thepresent invention (hereinafter, also referred to as first circuitsubstrate). In such a first circuit substrate according to the presentinvention, environmental loads, material costs, and equipment investmentcosts in the production steps can be reduced.

The present invention is also a circuit substrate including a gatewiring, a source wiring, and a semiconductor element on a substrate,wherein the circuit substrate constitutes a display device or an imagingdevice; the circuit substrate includes a configuration in which asemiconductor element in a display region or an imaging region isdisposed on a group of parallel lines extending in an extendingdirection of the gate wiring and/or the source wiring and aconfiguration in which a semiconductor element in a non-display regionor a non-imaging region is disposed on the group of parallel lines(hereinafter, also referred to as second circuit substrate). In such asecond circuit substrate of the present invention, the resist materialor the solvent is added dropwise by scanning the injection head in theextending direction of the gate wiring and/or the source wiring, usingthe production method of the semiconductor element of the presentinvention. As a result, the semiconductor elements in the display regionand those in the non-display region can be simultaneously produced inproduction of the circuit substrate constituting a display device, andthe semiconductor elements in the imaging region and those in thenon-imaging region can be simultaneously produced in production of thecircuit substrate constituting an imaging device. Therefore,environmental loads, material costs, and equipment investment costs inthe production of the circuit substrate can be reduced, and the processtime can be also shortened. The above-mentioned circuit substrate mayhave a configuration in which the semiconductor element in the displayregion or the imaging region and the semiconductor element in thenon-display region or the non-imaging region are disposed on a commongroup of parallel lines extending in the extending direction of the gatewiring and/or the source wiring, and simultaneously have a configurationin which a semiconductor element is disposed on another group ofparallel lines extending in the extending direction of the gate wiringand/or the source wiring. In the above-mentioned circuit substrate,other semiconductor elements may be disposed, in addition to thesemiconductor element disposed on the group of parallel lines extendingin the extending direction of the gate wiring or the source wiring.Preferable embodiments of the above-mentioned circuit substrate includean active matrix substrate in which semiconductor elements that areactive elements are arrayed in a matrix pattern in the display region orthe imaging region.

If the second circuit substrate of the present invention is produced bythe first to third production method of the semiconductor element of thepresent invention, the source wiring connected to the source electrodeof the semiconductor element also has a semiconductor layer on thesubstrate side. Such a circuit substrate generally has an embodiment inwhich the semiconductor layer is formed on the entire surface on thesubstrate side of the source wiring connected to the source electrode.

The present invention is also a circuit substrate including a gatewiring, a source wiring, and a semiconductor element on a substrate,wherein the circuit substrate constitutes a display device or an imagingdevice; the circuit substrate includes a configuration in which asemiconductor element in a display region or an imaging region isdisposed on a group of parallel lines extending in an extendingdirection of the gate wiring and/or the source wiring (also referred toas first group of parallel lines) and a configuration in which asemiconductor element in a non-display region or a non-imaging region isdisposed on a group of straight lines determined based on a unitfraction of a distance between the parallel lines (also referred to assecond group of parallel lines) (hereinafter, also referred to as thirdcircuit substrate). Also in such a third circuit substrate of thepresent invention, the resist material or the solvent is added dropwiseby scanning the injection head in the extending direction of the gatewiring and/or the source wiring, using the production method of thesemiconductor element of the present invention, as in the second circuitsubstrate of the present invention. As a result, the semiconductorelements in the display region and those in the non-display region canbe simultaneously produced in production of the circuit substrateconstituting a display device, and the semiconductor elements in theimaging region and those in the non-imaging region can be simultaneouslyproduced in production of the circuit substrate constituting an imagingdevice. Therefore, environmental loads, material costs, and equipmentinvestment costs in the production of the circuit substrate can bereduced, and the process time can be also shortened. In theabove-mentioned circuit substrate, other semiconductor elements may bedisposed, in addition to the semiconductor element disposed on the groupof parallel lines extending in the extending direction of the gatewiring or the source wiring.

Preferable embodiments of the above-mentioned circuit substrate includean active matrix substrate in which semiconductor elements that areactive elements are arrayed in a matrix pattern in the display region orthe imaging region.

If the third circuit substrate of the present invention is produced bythe first to third production method of the semiconductor element of thepresent invention, the source wiring connected to the source electrodeof the semiconductor element also has a semiconductor layer. Such acircuit substrate generally has an embodiment in which the semiconductorlayer is formed on the entire surface on the substrate side of thesource wiring connected to the source electrode.

It is preferable that the second and third circuit substrates of thepresent invention have a configuration in which the semiconductorelement in the display region or the imaging region is disposed on agroup of parallel lines extending in the extending direction of the gatewiring. As a result, if the production method of the semiconductorelement according to the present invention is used, the injection headis scanned in the extending direction of the gate wiring and thereby theresist material or the solvent can be added dropwise. In the circuitsubstrate such as a TFT array substrate, many gate wirings and sourcewirings are disposed to be perpendicular to each other. The distancebetween adjacent gate wirings (gate wiring pitch) is generally largerthan that between adjacent source wirings (source wiring pitch).Therefore, the second resist pattern film is successively applied andformed in the gate wiring direction, and thereby the number of thenozzle machinery formed in the injection head can be reduced. Therefore,the injection head is easy to prepare, which leads to reduction inequipment investment costs.

In the second and third circuit substrates according to the presentinvention, it is preferable that a plurality of semiconductor elementsdisposed in the display region or the imaging region are disposed atevery intersection of the gate wiring with the source wiring; and theplurality of semiconductor elements disposed at every intersection areconfigured to be disposed on one group of parallel lines extending inthe extending direction of the gate wiring or the source wiring. As aresult, even if more than one semiconductor element is disposed in eachpixel, the semiconductor elements on the circuit substrate can beproduced with efficiency.

In the second and third circuit substrates according to the presentinvention, it is preferable that the semiconductor element disposed inthe display region or the imaging region is a thin film transistor. Thethin film transistor can be preferably produced by the production methodof the semiconductor element of the present invention. Excellent displayquality or imaging quality can be obtained by switching a voltageapplied to an electrode formed in the display region or the imagingregion using the thin film transistor. It is also preferable that thesemiconductor element disposed in the non-display region or thenon-imaging region is a thin film diode. The thin film diode can bepreferably produced by the production method of the semiconductorelement of the present invention. If the thin film diode is disposed inthe non-display region, electrostatic discharge damage in a switchingelement such as a thin film transistor formed in the display region orthe non-display region can be prevented and excellent display qualitycan be obtained.

The present invention is also an electron device including a circuitsubstrate produced by the production method of the circuit substrate ofthe present invention or including the circuit substrate of the presentinvention. According to such an electron device of the presentinvention, environmental loads, material costs, and equipment investmentcosts in the production steps can be reduced. Preferable examples of theelectron device of the present invention include an imaging device, adisplay device, and an image input device. A flat panel X-ray imagesensor device and the like may be mentioned as the imaging device. Theflat panel X-ray image sensor device has a structure, for example, inwhich an X-ray receiving layer and a circuit for reading a chargeaccumulated in an imaging region are disposed on a TFT array substrate,and is used in a medical application, an X-ray examination application,and the like. A liquid crystal display device, an organicelectroluminescent display device and the like are preferably used asthe display device.

EFFECT OF THE INVENTION

According to the production method of the thin film pattern of thepresent invention, in the step of forming the second resist patternfilm, the fluid resist material is applied on the groove of the bankpattern formed using the first resist pattern film. As a result, thesecond resist pattern film can be formed with high accuracy even bycoating, and the number of photolithography processes needed forpatterning can be reduced. Therefore, such a production method of thethin film pattern can be preferably used for production of asemiconductor element formed on a circuit substrate and the like.

BEST MODES FOR CARRYING OUT THE INVENTION

The present invention is mentioned in more detail below with referenceto Embodiments, but the present invention is not limited to only theseEmbodiments.

Embodiment 1

As one Embodiment of the present invention, a production method of aninverse stagger type amorphous silicon TFT (thin film transistor)according to Embodiment 1 is mentioned with reference to FIGS. 1 to 11.

The production method of the TFT according to the present Embodimentincludes, as shown in FIG. 1, a gate electrode-forming step 1, a gateinsulating film and semiconductor film-forming step 2, a source metalfilm and resist film-forming step 3, a source metal film andsemiconductor film-etching step 4, a resist film at channel-forming step5, and a channel-forming step 6. The characteristic of the presentEmbodiment is that a source electrode and a drain electrode are formedand then, a droplet of a resist material is added into the centerbetween these electrodes with an ink-jet device to form an additionalresist pattern film (a second resist pattern film) and that asemiconductor film is patterned using the second resist pattern film asa mask.

FIG. 2( a) is a planar view schematically showing a TFT prepared by theproduction method of the present Embodiment and a configuration near theTFT; and FIG. 2( b) is a cross-sectional view schematically showing theconfiguration taken along line A-A in FIG. 2( a).

A TFT 7 prepared in the present Embodiment has a bottom gate structure,as shown in FIGS. 2( a) and (b), and has a configuration in which a gateelectrode 10 branched from a gate wiring 9, a gate insulating film 11,an amorphous silicon layer 12, an n⁺ type amorphous silicon layer 13, asource electrode 15 branched from a source wiring 14, a drain electrode17 connected to a drain connecting wiring 16 are stacked on a glasssubstrate 8.

In the amorphous silicon layer 12, a portion between the sourceelectrode 15 and the drain electrode 17 is a TFT channel 18. The drainconnecting wiring 16 is formed for connecting a pixel electrode (notshown) and the drain electrode 17, for example, in a displayapplication. On the upper side of the source electrode and the drainelectrode in a commonly used TFT such as the TFT according to thepresent Embodiment, a passivation film is often formed to cover the TFTchannel, which is not shown in FIG. 2.

For preparation of the TFT 7 of the present embodiment, an ink-jetdevice was used as a pattern-forming device capable of selectivelyinjecting or adding dropwise a fluid material as a droplet on thesubstrate surface. This ink-jet device, as shown in FIG. 3, includes amounting base (substrate stage) 20 on which a substrate 19(corresponding to a glass substrate 8 in FIG. 2) is placed, and alsoincludes an ink-jet head 21 as droplet-injecting means for injecting oradding dropwise a fluid material as a droplet on the substrate 19 placedon this mounting base, an X direction driving part 22 moving the ink-jethead 21 in X direction, and an Y direction driving part 23 moving theink-jet head 21 in Y direction.

The ink-jet device also includes an ink feeding system 24 for supplyingthe fluid material into ink-jet head 21, and a control unit 25 whichperforms various controls such as injection control of the ink-jet head21 and driving control of the X direction driving part 22 and the Ydirection driving part 23. From the control unit 25, information oninjection position is output into the X direction driving part 22 andthe Y direction driving part 23 and injection information is output intoa head driver (not shown) of the ink-jet head 21. As a result, theink-jet head 21 is driven in conjunction with the X direction drivingpart 22 and the Y direction driving part 23, and thereby a desiredamount of the droplet is added into a desired position on the substrate19.

A piezo system ink-jet head using a piezo actuator and a bubble systemink-jet head including a heater may be used as the ink-jet head 21. Theamount of the droplet injected from the ink-jet head 21 is controlled bycontrol of an applied voltage and the like.

The system of injecting the droplet in the pattern formation device usedin the present invention is not limited to the ink-jet method, as longas it is a system capable of injecting or adding the fluid material as adroplet. A system of simply adding a droplet may be used.

In the present Embodiment, a fluid resist material including a resin andan organic solvent was used as the fluid material injected or addeddropwise with the ink-jet device. In the present Embodiment, a resistmaterial without photosensitivity was used, but a resist material withphotosensitivity may be used. According to the present Embodiment, it ispreferable that a film formed of the resist material has a resistanceproperty for a dray-etching treatment and a property of being easilyremoved by a chemical and the like. Therefore, it is preferable that aresist material capable of showing such properties is used.

In the present invention, the fluid material is not limited to thesematerials, and it may be a fluid resist material containing a resin andan inorganic solvent such as water, a fluid material containing somesolid contents and an organic or inorganic solvent, or a fluid materialcomposed of an organic solvent and/or an inorganic solvent. The fluidmaterial may contain an additive such as a photosensitizing agent.

The production method of the TFT 7 according to the present Embodimentis mentioned below in more detail with reference to each step shown inFIG. 1.

“Gate Electrode-Forming Step 1”

FIG. 4( a) is a planar view schematically showing a configuration afterthe gate electrode-forming step 1 in the production process of the TFT7; and FIG. 4( b) is across-sectional view schematically showing theconfiguration taken along line B-B in FIG. 4( a). In FIG. 4, a gateelectrode 10 and the like is formed on a glass substrate 8.

In this step, a titanium (Ti) film was formed on the glass substrate 8to have a thickness of 0.2 μm by sputtering at a film formationtemperature of 100° C. As a result, a gate metal film made of titaniumwas obtained. Then, on this gate metal film, a resist pattern film wasformed using a resist material, and by a series of methods in whichpatterning was performed using this resist pattern film as a mask, thatis, a photolithography process, the gate electrode 10 and the like wasformed. A dry-etching method was adopted as a method of etching the gatemetal film at this time. Chlorine (Cl₂) gas and boron trichloride (BCl₃)gas were used in combination as an etching gas. Then, the photoresistfilm was removed using an organic solvent and the like.

In the present Embodiment, a first photolithography process wasperformed in this step.

In the present invention, the metal forming the gate metal film is notespecially limited. For example, metals and metal compounds such asaluminum (Al), copper (Cu), chromium (Cr), tantalum (Ta), molybdenum(Mo), indium tin oxide (ITO), titanium, and molybdenum (Mo) may be used.The gate metal film may be composed of a single layer, or may have amultilayer structure. The method of forming the gate metal film is notespecially limited, and a deposition method and the like may be used, inaddition to the sputtering. The film thickness of the gate metal film isnot especially limited. The method of etching the gate metal film is notespecially limited, and a wet-etching method and the like may be used.

“Gate Insulating Film and Semiconductor Film-Forming Step 2”

FIG. 5( a) is a planar view schematically showing a configuration afterthe gate insulating film and semiconductor film-forming step 2 in theproduction process of the TFT 7; and FIG. 5( b) is a cross-sectionalview schematically showing the configuration taken along line C-C inFIG. 5( a). In FIG. 5, on the glass substrate 8 after the gateelectrode-forming step 1, a gate insulating film 11, an amorphoussilicon film 27, and an n⁺ type amorphous silicon film 28 are formed.The gate insulating film 11 was made of silicon nitride (SiN_(x)). Thesefilms were successively formed by a plasma enhanced chemical vapordeposition (CVD) method at 300° C. in a vacuum chamber. Each thicknessof the films was 0.4 μm (the gate insulating film 11), 0.2 μm (theamorphous silicon film 27), and 0.1 μm (the n⁺ type amorphous siliconfilm 28). In the present invention, the forming method and the thicknessof each film are not especially limited.

“Source Metal Film and Resist Film-Forming Step 3”

FIG. 6( a) is a planar view schematically showing a configuration afterthe source metal film and resist film-forming step 3 in the productionprocess of the TFT 7; and FIG. 6( b) is a cross-sectional viewschematically showing the configuration taken along line D-D in FIG. 6(a). In FIG. 6, on the glass substrate 8 after the gate insulating filmand semiconductor film-forming step 2, a source metal film 29 and aresist pattern film 30 are formed.

In this step, a titanium (Ti) film was formed to have a thickness of 0.2μm by the same method as in the gate metal film, and thereby the sourcemetal film 29 was formed. The source metal film 29 is patterned later toserve as a source electrode 15 and a drain electrode 17. The sourcemetal film 29 is not especially limited to the embodiment of the presentEmbodiment, as in the gate metal film.

Then, as one step of the photolithography process, the resist patternfilm 30 was formed on the source metal film 29 using a resist materialhaving photosensitivity (photoresist material). The resist pattern film30 had a film thickness of 2.5 μm.

“Source Metal Film and Semiconductor Film-Etching Step 4”

FIG. 7( a) is a planar view schematically showing a configuration afterthe source metal film and semiconductor film-etching step 4 in theproduction process of the TFT 7; and FIG. 7( b) is a cross-sectionalview schematically showing the configuration taken along line E-E inFIG. 7( a). In FIG. 7, the source metal film 29 and the n⁺ typeamorphous silicon film 28 were successively subjected to etchingtreatment using the resist pattern film 30 formed in the source metalfilm and resist film-forming step 3 as a mask, and thereby a sourcewiring 14, a source electrode 15, a drain electrode 17, an n⁺ typeamorphous silicon layer 13, and the like were formed. Then, a surfacetreatment was further performed. Accordingly, the TFT 7 of the presentEmbodiment includes semiconductor layers (an amorphous silicon layer 12and an n⁺ type amorphous silicon layer 13) on the entire surface on thesubstrate side of the source electrode 15, the drain electrode 17, andthe source wiring 14 connected to the source electrode 15.

In this step, a space 31 (also referred to as a TFT gap or channelgroove) formed between the source electrode 15 and the drain electrode17 was formed in such a way that a distance L between the sourceelectrode 15 and the drain electrode 17 was 3 μm and a width W of eachof the source electrode 15 and the drain electrode 17 was 60 μm.

In this step, a dry etching method was adopted as a method of etchingtreatment for the source metal film 29 and the n⁺ type amorphous siliconfilm 28, and chlorine (Cl₂) gas and boron trichloride (BCl₃) gas wereused in combination as an etching gas. The above-mentioned etchingtreatment method is not especially limited, and a wet-etching method andthe like may be used. In order to prevent a leak current between thesource electrode 15 and the drain electrode 17, the n⁺ type amorphoussilicon film 28 at the TFT gap 31 must be sufficiently removed by theabove-mentioned etching treatment. Accordingly, in the presentEmbodiment, an over-etching treatment may be performed to etch a part onthe upper layer side of the amorphous silicon 27, which is not shown inFIG. 7( b).

In this step, after completion of the dry etching treatment for the n⁺type amorphous silicon layer 13, a treatment of providing the surface ofthe resist pattern film 30 and the amorphous silicon film 27 and thelike with a lyophilic or lyophobic property for a resist liquid used inthe following step was performed. The lyophilic or lyophobic propertymeans a wettability or repellent property which a liquid shows when incontact with a solid surface. In the present Embodiment, in a vacuumchamber after completion of the dry etching treatment for the n⁺ typeamorphous silicon layer 13, the surface treatment was performed by aplasma treatment method using oxygen (O₂) gas and carbon tetrafluoride(CF₄) gas.

After this surface treatment, the surface was measured for contact angleto determine the lyophilic or lyophobic property. A method ofcalculating a contact angle by approximating it as a part of a sphere,which is a commonly used method, was employed as a method of measuringthe contact angle. As a result, the contact angle on the resist patternfilm 30 exposed on the substrate surface was 40° to 80° and the contactangle on the amorphous silicon film 27 was 20° to 30°. In contrast, ifthe surface treatment was not performed, each contact angle was 0° to10°. As mentioned above, the surface treatment provided the surface ofthe resist pattern film 30 and the amorphous silicon film 27 with thelyophilic or lyophobic property.

Each contact angle on the end surface exposed on the TFT gap 31 side ofthe n⁺ type amorphous silicon layer 13, the source electrode 15, and thedrain electrode 17 is estimated to be about 20° to 80° based onmeasurement results of a film surface which is made of the same materialand treated under the same conditions as in the present Embodiment.

The surface treatment method employed in the present invention is notespecially limited to the method of the present Embodiment, and anymethods may be used as long as the lyophilic or lyophobic property canbe adjusted. The above-mentioned contact angle is mentioned just as oneexample, and therefore it is not especially limited in the presentinvention.

In the present Embodiment, a second photolithography process wasperformed in this step and the previous step, that is, the source metalfilm and the resist film-forming step 3.

“Resist Film at Channel-Forming Step 5”

This step is mentioned with reference to FIGS. 8 to 10.

On the glass substrate 8 after the source metal film and semiconductorfilm-etching step 4, a droplet of a resist material (resist droplet) 32was injected into the center of the TFT gap 31 by an ink-jet method.FIG. 8( a) is a planar view schematically showing an image when theresist droplet is landed on the TFT gap 31; and FIG. 8( b) is across-sectional view schematically showing the configuration taken alongline F-F in FIG. 8( a).

In this step, the pattern forming device capable of selectivelyinjecting or adding a droplet of a fluid material on the substratesurface is used. In the present Embodiment, the ink-jet device was used,as mentioned above. A material mainly including novolak resin anddiethylene glycol monobutyl ether was used as the resist material. Theresist droplet 32 injected at this time had a volume of 1 to 2 pl.

As shown in FIG. 8( a), the resist droplet 32 has an almost circularplanar shape when landed. However, this planar shape depends on thedroplet shape while the resist droplet 32 is injected from the ink-jethead 21 of the ink-jet device and then dropped, and therefore it issufficiently possible that the resist droplet 32 has a shape other thanthe circular shape. After landed, the resist droplet 32 contacts withthe surface of the resist pattern film 30 and the surfaces of ends ofthe resist pattern film 30, the source electrode 15, the drain electrode17, and the n⁺ type amorphous silicon layer 13, each consisting the TFTgap 31, and the surface of the amorphous silicon film 27, as shown inFIG. 8( b).

In the present Embodiment, the ink-jet device was used as the patternforming device, but the pattern forming device is not especially limitedin the present invention. The resist material used in the presentEmbodiment had no photosensitivity, but in the present invention, thekind of the fluid material serving as the resist droplet and whether ornot the fluid material has photosensitivity are not especially limited.The number of the resist droplet injected into each TFT gap 31 is notnecessarily one, and two or more droplets may be injected. Theabove-mentioned volume of the resist droplet is mentioned just as oneexample, and it is not especially limited in the present invention. Thevolume of the resist droplet needs to be properly determined dependingon size of a desired pattern.

FIG. 9( a) is a planar view schematically showing a configuration inwhich the resist droplet 32 shown in FIG. 8( a) is deformed after landedbecause of its fluidity; and FIG. 9( b) is a cross-sectional viewschematically showing the configuration taken along line G-G in FIG. 8(a).

The resist droplet 32 was deformed to have a shape like a resist droplet33 shown in FIG. 9, after landed. Specifically, the resist droplet 32spread to fill the TFT gap 31 and had a shape having an intersurfacenear both ends 34 of the TFT gap 31. The shape of such a resist droplet33 was controlled and realized by the pattern shape (bank pattern) ofthe bank formed by the resist pattern film 30 and the like and thelyophilic or lyophobic property provided by the surface treatment in theprevious step.

The shape change of the resist droplet after landed is mentioned in moredetail. First, the resist droplet 32 immediately after landed gets wetand spreads over the surfaces of the resist pattern film 30 and theamorphous silicon film 27 because the contacting portion of the films 30and 27 shows a contact angle of 90° or less. The direction of the wetspread at this time is controlled by the unevenness formed by themultilayer structure of the resist pattern film 30, the source electrode15, the drain electrode 17, and the n⁺ type amorphous silicon layer 13,each constituting both sides of the TFT gap 30, that is, a bank. Thisbank controls the direction of the wet spread of the resist droplet andthe resist droplet gets wet and spreads inside the TFT gap 31. In thepresent Embodiment, the contact angle on the resist pattern film 30 washigher than that on the amorphous silicon film 27, and therefore theresist droplet preferentially enters the TFT gap 31.

As mentioned above, the resist droplet spreads inside the TFT gap 31,but its movement is stopped when the surface tension of the resistdroplet and the wet spread force are balanced. The resist droplet tendsto remain inside the TFT gap 31 and its vicinity as much as possible dueto capillarity and the surface tension of the resist droplet. In thepresent Embodiment, the amount and the viscosity of the resist dropletand the like were properly determined, and thereby the resist droplet 33which spreads near the both ends 34 of the TFT gap 31 could be obtained.

As mentioned above, the shape of the resist droplet can be controlled byusing the bank pattern, that is, the bank pattern including the openingat the both ends 34 of the TFT gap (open ends of the bank pattern), andthe bank having a multilayer structure of the resist pattern film 30constituting the both sides of the TFT gap 31, the source electrode 15,the drain electrode 17, and the n⁺ type amorphous silicon layer 13.

As mentioned below, the shape of the resist droplet 33 in the presentEmbodiment is mentioned just as one example, and it is not especiallylimited in the present invention.

FIG. 10( a) is a planar view schematically showing a configuration wherea resist pattern film 35 is formed inside the TFT gap 31; and FIG. 10(b) is a cross-sectional view schematically showing the configurationtaken along line H-H in FIG. 10( a).

The resist pattern film 35 was formed by volatilizing an organic solventincluded in the resist droplet 33 and subjecting the substrate to heattreatment at 120° C. Due to the volume shrinkage at this time, theinside of the resist droplet 33 became temporarily negative pressurestate, and part of the resist droplet 33, which flowed out of the bothends 34 of the TFT gap 31, was absorbed. As a result, the resist patternfilm 35 was formed to have a shape slightly changed from the shape shownin FIG. 9( a). Due to this function, the resist pattern film 35 at theTFT gap 31 tends to have a certain shape shown in FIG. 10 regardless ofvariation in conditions such as a contact angle.

In the present Embodiment, the organic solvent in the resist droplet 33was volatilized by being left. The heat treatment for the substrate wasperformed in order to improve a resistance for a dry-etching treatmentand the like to be performed in the following step. However, in thepresent invention, the method of volatilizing the organic solvent is notespecially limited, and a method of volatilizing the organic solvent byheating the substrate, and the like, may be appropriately selecteddepending on the kind of the contained organic solvent and the volume ofthe added resist droplet. In the present invention, the method ofheating the substrate is not especially limited.

“Channel-Forming Step 6”

FIG. 11( a) is a planar view schematically showing a configuration afterthe channel-forming step 6 in the production process of the TFT 7; andFIG. 11( b) is a cross-sectional view schematically showing theconfiguration taken along line I-I in FIG. 11( a). In FIG. 11, on thesubstrate after the resist film at channel-forming step 5, an amorphoussilicon layer 12 is obtained from the amorphous silicon film 27 byperforming a dry-etching treatment using the resist pattern film 30 andthe resist pattern film 35 as a mask.

In this step, chlorine (Cl₂) gas was used as an etching gas in thedry-etching treatment for the amorphous silicon film 27.

In the present Embodiment, the resist pattern films 30 and 35 wereremoved from the configuration shown in FIG. 11, and a TFT basicstructure in FIG. 2 was obtained. A TFT channel 18 was formed in aregion which was a lower layer of the TFT gap 31, in the amorphoussilicon layer 12. The shape of the TFT channel 18 reflects the shape ofthe resist pattern film 35 formed by the resist droplet.

As mentioned above, the number of photolithography processes performeduntil the TFT basic structure was obtained was two in the presentEmbodiment. However, in the present Embodiment, the step of forming theadditional resist pattern film 35 was separately performed using thepattern forming device such as the ink-jet device.

Comparative Embodiment 1

A production method of an inverse stagger type amorphous silicone TFTaccording to Comparative Embodiment 1 is mentioned with reference toFIGS. 12 and 13.

The production method of the TFT according to Comparative Embodiment 1,as shown in FIG. 12, includes a gate electrode-forming step 41, a gateinsulating film and semiconductor film-forming step 42, a resist filmfor semiconductor film process-forming step 43, a semiconductorisland-forming step 44, a source metal film and resist film-forming step45, and a source metal film and semiconductor film-etching step 46.

FIG. 13( a) is a planar view schematically showing a TFT prepared by theproduction method according to Comparative Embodiment 1 and aconfiguration near the TFT; and FIG. 13( b) is a cross-sectional viewschematically showing the configuration taken along line J-J in FIG. 13(a).

As shown in FIGS. 13( a) and (b), a TFT 47 prepared in ComparativeEmbodiment 1 has a bottom gate structure, as in Embodiment 1, and has aconfiguration in which a gate electrode 50 branched from a gate wiring49, a gate insulating film 51, an amorphous silicon layer 52, an n⁺ typeamorphous silicon layer 53, a source electrode 55 branched from a sourcewiring 54, a drain electrode 57 connected to a drain connecting wiring56 are stacked on a glass substrate 48.

In the amorphous silicon layer 52, a portion between the sourceelectrode 55 and the drain electrode 57 is a TFT channel 58. The TFT 47formed in the present Comparative Embodiment is different from the TFT 7formed in Embodiment 1 in that the amorphous silicon layer 52 and the n⁺type amorphous silicon layer 53 are processed to have an island shape onthe upper layer side of the gate insulating film 51. Also in the presentComparative Embodiment, the passivation film covering the TFT channel 58is not shown.

The production method of the TFT 47 according to Comparative Embodiment1 is simply mentioned.

First, as in Embodiment 1, the gate electrode-forming step 41 isperformed to form the gate electrode 50 and the like. In the presentComparative Embodiment, a first photolithography process is performed inthe gate electrode-forming step 41.

Then, the gate insulating film 51, and the island-shaped amorphoussilicon layer 52 and n⁺ type amorphous silicon film are formed throughthe gate insulating film and semiconductor film-forming step 42, theresist film for semiconductor film process-forming step 43, and thesemiconductor island-forming step 44. In the present ComparativeEmbodiment, a second photolithography process is performed during thesesteps.

Then, the source metal film and resist film-forming step 45 and thesource metal film and semiconductor film-etching step 46 are performed.As a result, the source electrode 55 and the drain electrode 57 areformed, and simultaneously, the n⁺ type amorphous silicon film at theportion between these electrodes is removed, thereby electricallyseparating the source electrode 55 from the drain electrode 57. In thepresent Comparative Embodiment, a third photolithography process isperformed in this step.

As mentioned above, according to the production method of ComparativeEmbodiment 1, a total of at least three photolithography processes areneeded for obtaining such a TFT basic structure if specialphotolithography such as halftone exposure method is not performed.

Comparison of Embodiment 1 with Comparative Embodiment 1

In Embodiment 1 according to the present invention, one photolithographyprocess was replaced with the resist pattern film formation using theink-jet method. Therefore, one photolithography process could beomitted, which leads to reduction in use amount of chemicals such as aresist material, a developer, a resist-separating solution. Strictly,also in the ink-jet method, the fluid material such as the resistmaterial is used, but the material is selectively injected, andtherefore the use amount thereof is much smaller. Therefore, from aviewpoint of production of TFTs, the method in Embodiment 1 possessesadvantages such as decrease in material costs and reduction in influenceon ambient environment (environmental loads) associated with chemicaluse.

In a large-scale production of TFTs, such reduction in the number ofphotolithography processes leads to decrease in the number of veryexpensive exposure devices as typified by a proximity exposure deviceand a step type exposure device (stepper). Therefore, an effect ofreduction in equipment investment costs of the production line as awhole may be mentioned. Reduction in equipment investment costsgenerally contradicts reduction in material costs, for example, becauseexpensive materials must be used in order to reduce the equipmentinvestment costs. Therefore, according to the production method inEmbodiment 1, both of the material costs and the equipment investmentcosts can be reduced.

Comparison of Embodiment 1 with a Production Method Using a HalftoneExposure Method

The use of the halftone exposure method also can provide the same TFTbasic structure through the same number of photolithography processes asin Embodiment 1, for reference. However, the production method inEmbodiment 1 is superior in that TFTs can be prepared by a generalphotolithography technique. First, no special photomask for halftoneexposure is needed. Therefore, a wide process margin in an exposurecondition, a development condition, and the like can be permitted, andthe contact angle on the film surface on the substrate, the shape andthe like of the source electrode and the drain electrode and the likecan be controlled. As a result, the shape of the TFT channel can be moreeffectively controlled. Secondly, the source wiring and the like ispatterned using the resist pattern film immediately after formed by theexposure and the development as a mask. Therefore, variation in patternsuch as variation in wiring thickness can be reduced in comparison tothe halftone exposure method using a resist pattern film after resistretreating (thinning) by ashing. Therefore, a TFT array substrateincluding TFTs having uniform electrical characteristics in thesubstrate surface can be formed. If such a TFT array substrate is usedin a display device, for example, display unevenness and the like isreduced and reduction in display quality can be prevented.

Comparison of Embodiment 1 with a Production Method in Patent Document 5

The production method in the above-mentioned Patent Document 5 is thesame as that in the present Embodiment in that the resist droplet isinjected with a pattern formation device such as ink-jet device, andusing the obtained resist pattern film as a mask, the semiconductor filmis subjected to the patterning process.

The production method described in the above-mentioned Patent Document 5is mentioned below with reference to FIGS. 14 and 15.

FIGS. 14( a) and 15(a) are planar views each schematically showing aconfiguration of a TFT prepared by the production method of theabove-mentioned Patent Document 5. FIG. 14( b) is a cross-sectional viewschematically showing the configuration taken along line K-K in FIG. 14(a). FIG. 15( b) is a cross-sectional view schematically showing theconfiguration taken along line L-L in FIG. 15( a). Components havingsubstantially the same function are expressed by the same symbol inFIGS. 14 and 15.

The structure of the TFTs 61 and 70 shown in FIGS. 14 and 15 ismentioned. On a glass substrate 62, a gate electrode 63 is disposed andthereover a gate insulating film 64 is covered. As an upper layer of thegate insulating film 64, an amorphous silicon layer 65 or 71 isdisposed, and a source electrode 66 and a drain electrode 67 aredisposed as an upper layer of the amorphous silicon layer 65 or 71.Between the amorphous silicon layer 65 or 71, and the source electrode66 and the drain electrode 67, an n⁺ type amorphous silicon layer 68 or73 is disposed.

The amorphous silicon layers 65 and 71 are prepared by patterning anamorphous silicon film formed on the entire surface of the substrateusing a resist pattern film formed with an ink-jet device as a mask. Inthe ink-jet device, the landing accuracy is generally inferior toalignment accuracy of an exposure device such as a stepper, and thelanding position tends to vary depending on droplets. Particularly ifthe ink-jet head has many nozzles, the landing accuracy varies among thenozzles. With respect to landing accuracy of a common ink-jet device,droplets are landed at least 5 to 10 μm or more away from the center ofthe target position. Such a landing accuracy is inferior to thealignment accuracy of the exposure device by about 10 times.

The TFT 61 shown in FIG. 14 shows a TFT formed in the case where theresist droplet is landed on the center of the TFT-formed portion. TheTFT 70 shown in FIG. 15 is a TFT formed in the case where the resistdroplet is landed away from the center. In these TFTs 61 and 70, thepositions where the amorphous silicon layers 65 and 71 are formed aredifferent because of difference in the position where the resist dropletis landed. On/off current characteristics as a switching element areimportant for TFTs, but it is also important that an internalcapacitance of the TFT such as a capacity formed between the gateelectrode 63 and the drain electrode 67 is uniform. However, in the TFTs61 and 70, the capacity between the gate electrode 63 and the drainelectrode 67 is mainly formed in shaded regions 69 and 72 shown in FIGS.14( a) and 15(a), but these areas are clearly different, and thereforethe TFTs 61 and 70 have different internal capacitances. Morespecifically, in the TFT 61, the entire n⁺ type amorphous silicon layer68 is under the drain electrode 67, but in the TFT 70, the n+amorphoussilicon layer 73 is only under the drain electrode 67 in the shadedregion 72. Therefore, the TFTs 61 and 70 have different internalcapacitances.

As mentioned above, in the conventional production method shown in theabove-mentioned Patent Document 5, the landing position of the resistdroplet injected from the ink-jet device varies, and therefore theinternal capacitance of the TFT formed by this method varies in thesubstrate surface. Accordingly, if such a TFT array substrate is used ina display device, for example, pixel electrodes connected to the TFTshave different potentials, which reduces the display quality. Asmentioned above, according to the conventional production method shownin the above-mentioned Patent Document 5, it is difficult to form a TFTarray substrate with uniform electrical characteristics in the substratesurface.

The production method in Embodiment 1 is different from such a method inthat the source electrode 15 and the drain electrode 17 are formed infirst; the unevenness formed by the multilayer structure of the resistpattern film 30 on both sides of the TFT gap 31, the source electrode15, the drain electrode 17, and the n⁺ type amorphous silicon layer 13is used as a bank for controlling the shape of the resist droplet.Therefore, the method of Embodiment 1 prevents variation in internalcapacitance among TFTs.

Experimental Example 1

In the present Experimental Example, whether or not the landing accuracyof the resist droplet, which is needed for the ink-jet device inEmbodiment 1, is more reduced in comparison with the above-mentionedproduction method of the Patent Document 5, was examined. FIG. 16 is anenlarged planar view schematically showing a part (FIG. 7( a)) aftercompletion of the source metal film and semiconductor film-etching step4 in Embodiment 1.

In FIG. 16, a distance L between the source electrode 15 and the drainelectrode 17 is 3 μm; a width W of each of the source electrode 15 andthe drain electrode 17 is 60 μm; and a length D of each of the sourceelectrode 15 and the drain electrode 17 is 16 μm. In FIG. 16, the gateelectrode 10, the gate insulating film 11, and the like are not shown.Other conditions are the same as those mentioned in Embodiment 1.

A method in which a resist droplet was intentionally landed on aposition away from the center of the TFT gap 31 shown by x to form aresist pattern film and this resist pattern film was observed for shapewith a light microscope of 500 magnifications, was used as anexperimental method. As for criterion, a resist pattern film which wasinside the TFT gap 31 and had an end within ±3 μm from the both ends 34was estimated as “good”, and other films were estimated as “bad”. Thatis, a resist pattern film like the resist pattern film 35 shown in FIG.10( a) was estimated as “good”, and a resist pattern film formed outsideof the both ends 34 was estimated as “bad”. The following Table 1 showsthe results.

TABLE 1

The X-coordinate and the Y-coordinate in Table 1 represent a distancefrom the center of the TFT gap 31 (unit; μm). The directions of theX-axis and the Y-axis are those shown in FIG. 16, respectively.

As shown in Table 1, in the method of Embodiment 1, all pattern filmswhich showed an X coordinate of −6 to +6 μm and a Y-coordinate of −9 to+6 μm were estimated as “good.” That is, from a viewpoint of the radiusfrom the center of the TFT gap 31, all cases where the droplet waslanded on a position within a 6 μm radium were estimated as “good”.

Therefore, the landing accuracy needed for the ink-jet device is withina 6 μm radius, and within this range, the shape of the TFTs can bealmost uniform.

In contrast, according to the production method of the above-mentionedPatent Document 5, the internal capacitance varied among the TFTs andtherefore the characteristics thereof were reduced, if the distance Lbetween the source electrode 15 and the drain electrode 17 was 3 μm andthe landing accuracy of the ink-jet device was 5 to 10 μm or more.

As mentioned above, according to the production method in Embodiment 1,the landing accuracy of the pattern formation device such as an ink-jetdevice can be reduced. Therefore, the shape of TFTs in the substratesurface can be uniform in the substrate surface and reduction in displayquality of a liquid crystal display device and the like produced usingthis TFT substrate can be prevented.

(Further Note)

It has been known that a bank is formed on a substrate when an ink-jetmethod is used. If a wiring and the like is formed by an ink-jet method,for example, a technology in which a bank pattern is formed to surrounda wiring-formed region and an upper part of this bank pattern isprovided with a lyophobic property and the wiring-formed region isprovided with a lyophilic property, and thereby the landing accuracyneeded for the ink-jet device is reduced, is disclosed as in theabove-mentioned Patent Document 4. However, in this technology, adroplet of an ink material and the like is added into the regionsurrounded by the bank.

In contrast, the bank pattern in Embodiment 1 has an opening at the bothends 34, as mentioned above. That is, the bank pattern used inEmbodiment 1 has a bank at a position above the source electrode 15 andthe drain electrode 17, but has no bank at the both ends 34 of the TFTchannel 31. In the present invention, the use of the bank pattern havingan opening permits such a process method as in Embodiment 1 in which apair of electrodes are formed in the same plane, like the sourceelectrode 15 and the drain electrode 17 of the TFT 7, and a resistdroplet is added at a position corresponding to the space between theelectrodes. Thereby, a thin film element such as a TFT can be preparedthrough a smaller number of steps in comparison to the conventionalmethod.

In the bank pattern formation in the conventional technology,photolithography is purposely used for forming wirings and the like, andtherefore reduction in the number of photolithography processes can notbe expected. However, in Embodiment 1, the landing accuracy needed forthe ink-jet device can be reduced without additional steps of forming abank pattern and increase in the number of photolithography processes,because the unevenness formed by the multilayer structure of the resistpattern film 30 on the both ends of the TFT gap 31, the source electrode15, the drain electrode 17, and the n⁺ type amorphous silicon layer 13is used as a bank pattern.

Modified Embodiment of Embodiment 1

In Embodiment 1, the resist pattern film 35 shown in FIGS. 10( a) and(b) was obtained, but the shape of the resist pattern film is notespecially limited in the present invention.

The resist pattern film may be slightly out of the TFT gap 31 and partof the film may be formed on the upper part of the resist pattern film30, as shown in FIG. 17( a). FIG. 17( b) is a cross-sectional viewschematically showing the configuration taken along line M-M in FIG. 17(a).

The resist pattern film may be formed only near the center of the TFTgap 31, as shown in FIG. 18( a), for example. Such a shape can be formedby reducing the amount of the resist droplet or increasing the contactangle at the position where the resist droplet is added. For example,the contact angle on the resist pattern film 30 exposing on thesubstrate surface may be adjusted to 40° to 80°, and the contact angleon the amorphous silicon film 27 may be adjusted to 40° to 60°. Also inthis case, the lyophilic or lyophobic property on the substrate surfaceis property adjusted, and thereby landing error of the ink-jet devicecan be compensated. As a result, the shape of the TFTs in the substratesurface could be uniform.

In Embodiment 1, the surface treatment in the source metal film andsemiconductor film-etching step 4 was performed by the plasma treatmentmethod using oxygen (O₂) gas and carbon tetrafluoride (CF₄) gas. Forexample, a method of forming a film with a desired lyophilic orlyophobic property (lyophilic or lyophobic film) on the surface and thelike may be used. The lyophilic or lyophobic film may be a thin filmcomposed of a multiple molecular material or a monomolecular film. Fluidmaterials composed of resin materials such as alkylsilane, fluorinatedalkylsilane, acrylic resin, novolak resin, silicone resin, and fluorineresin, and organic solvents such as alcohols and fluorine solvents orwater may be used as a material for forming the lyophilic or lyophobicfilm. A spray method, a vapor deposition method, a CVD method, asputtering method, a spin coat method, an immersion method, and anink-jet method may be mentioned as a method of forming the lyophilic orlyophobic film. Such a method may be used in combination with theabove-mentioned plasma treatment method. Further, the lyophilic orlyophobic film may remain inside the TFT structure. For example, in FIG.19( a), the lyophilic or lyophobic film 76 remains at the TFT gap 31.FIG. 19( b) is a cross-sectional view schematically showing theconfiguration taken along line O-O in FIG. 19( a).

Embodiment 2

A production method of an inverse stagger type amorphous silicon TFTaccording to Embodiment 2 is mentioned with reference to FIGS. 20 to 22.In FIGS. 20 to 22, components having substantially the same function asin Embodiment 1 are expressed by the same symbol.

The present Embodiment is the same as Embodiment 1 in that the sourceelectrode 15 and the drain electrode 17 were formed by the patterningprocessing using the resist pattern film and then a resist materialdroplet injected with the ink-jet device was landed on the center ofthese electrodes to form an additional resist pattern film and thatusing the additional resist pattern film as a mask, the semiconductorfilm was subjected to the patterning process. The present Embodiment isdifferent from Embodiment 1 in that the resist pattern film on thesource wiring 14, the source electrode 15, and the drain electrode 17and the like was removed, and then the additional resist pattern filmwas formed.

Specifically, the production method of the TFT in the present Embodimentincludes, as shown in FIG. 20, the gate electrode-forming step 1, thegate insulating film and semiconductor film-forming step 2, the sourcemetal film and resist film-forming step 3, a source metal film andsemiconductor film-etching step 81, a resist film at channel-formingstep 82, and a channel-forming step 83. Among them, the gateelectrode-forming step 1, the gate insulating film and semiconductorfilm-forming step 2, and the source metal film and resist film-formingstep 3 are the same as in Embodiment 1, and therefore the explanationthereof is omitted. The TFT produced in the present Embodiment hasalmost the same shape as in the TFT produced in Embodiment 1, shown inFIG. 2.

“Source Metal Film and Semiconductor Film-Etching Step 81”

In this step, a treatment of separating and removing the resist patternfilm 30 was performed in addition to the source metal film andsemiconductor film-etching step 4 in Embodiment 1. FIG. 21( a) is aplanar view schematically showing a configuration after completion ofthe source metal film and semiconductor film-etching step 81; and FIG.21( b) is a cross-sectional view schematically showing the configurationtaken along line P-P in FIG. 21( a).

The resist pattern film 30 was removed after the etching treatment forthe source metal film 29 and the n⁺ type amorphous silicon film 28.

Then, as a substrate surface treatment, a specific lyophilic orlyophobic property was provided for the substrate surface by a plasmatreatment using oxygen (O₂) gas and carbon tetrafluoride (CF₄) gas.After this surface treatment, the contact angle was measured using theresist material. The source electrode 15 and the drain electrode 17,exposed on the substrate surface, had a contact angle of 40° to 50°, andthe amorphous silicon film 27 had a contact angle of 20° to 30°. Thatis, the lyophilic or lyophobic property for the resist material could beprovided, as in Embodiment 1. The end surface of the n⁺ type amorphoussilicon layer 13 exposed on the TFT gap 31 side may have a contact angleof about 20° to 80°. This is estimated from the results obtained bysubjecting the film surface made of the same material to the treatmentunder the same conditions.

Also in the present Embodiment, the above-mentioned surface treatmentmay be a treatment of forming a film having a lyophobic property for theresist droplet. The above-mentioned contact angle value is mentionedjust as one example, and it is not especially limited in the presentinvention.

“Resist Film at Channel-Forming Step 82”

This step is mentioned with reference to FIG. 22. FIG. 22( a) is aplanar view schematically showing a configuration after completion ofthe resist film at channel-forming step 82; and FIG. 22( b) is across-sectional view schematically showing the configuration taken alongline Q-Q in FIG. 22( a).

In this step, as in Embodiment 1, a resist droplet was injected on theglass substrate 8 after the above-mentioned source metal film andsemiconductor film-etching step 81, using the ink-jet device. As aresult, an additional resist pattern 84 was formed at the TFT gap 31.

Also in the present Embodiment, the reason why the resist pattern film84 was formed to mainly fill the TFT gap 31 is the same as inEmbodiment 1. However, in the present Embodiment, the unevenness formedby the multilayer structure of the source electrode 15, the drainelectrode 17, and the n⁺ type amorphous silicon layer 13 on both sidesof the TFT gap 31 serves as a bank for saving the resist droplet,although in Embodiment 1, the unevenness formed by the multilayerstructure of the resist pattern film 30, the source electrode 15, thedrain electrode 17, and the n⁺ type amorphous silicon layer 13 on bothsides of the TFT gap 31 serves as a bank for saving the resist droplet.That is, Embodiment 1 and the present Embodiment have different bankmultilayer structures. However, also in the present Embodiment, theshape of the resist droplet can be controlled by using the bank pattern,that is, the bank pattern including the opening at the both ends 34 ofthe TFT gap (open end of the bank pattern) and the banks at the sourceelectrode portion and the drain electrode portion on the both sides ofthe TFT gap 31.

“Channel-Forming Step 83”

In this step, the substrate after completion of the above-mentionedresist film at channel-forming step 82 was subjected to a dry-etchingtreatment, and thereby the amorphous silicon layer 12 was obtained fromthe amorphous silicon layer 27. In the dry etching treatment, carbontetrafluoride (CF₄) gas, oxygen (O₂) gas, and the like were used incombination as an etching gas, and the source electrode 15, the drainelectrode 17, and the resist pattern film 84 were used as a mask. As aresult, such a TFT basic structure as shown in FIG. 2 was obtained. TheTFT channel 18 was formed at a region which was a lower layer of the TFTgap 31, in the amorphous silicon layer 12. The shape of the TFT channel18 reflects the shape of the resist pattern film 84.

As mentioned above, the present Embodiment is the same as Embodiment 1also in that the number of photolithography processes performed in thepresent Embodiment was two and the ink-jet device was used as a patternformation device. Accordingly, in the present Embodiment as well asEmbodiment 1, the number of photolithography processes is reduced andadvantages such as reduction in material costs, environmental loads, andequipment investment costs in production of TFTs can be obtained.

The production method in the present Embodiment is the same as inEmbodiment 1 in that the source electrode 15 and the drain electrode 17are formed in first and that the bank pattern having an opening isformed. Therefore, as in Embodiment 1, a thin film element such as a TFTcan be prepared through a smaller number of production steps incomparison to the conventional production method. Also with respect tocomparison with the conventional technology, the production method inthe present Embodiment is the same as in Embodiment 1.

In the present invention, the shape of the resist pattern film 84 andthe surface treatment method in the source metal film and semiconductorfilm-etching step 81 and the like are not especially limited and may bevariously changed as in Embodiment 1.

Embodiment 3

A production method of an inverse stagger type amorphous silicon TFTaccording to Embodiment 3 is mentioned with reference to FIGS. 23 to 26.In FIGS. 23 to 26, components having substantially the same function asin Embodiment 1 are expressed by the same symbol.

The present Embodiment is the same as Embodiment 1 in that the sourcewiring 14, the source electrode 15, the drain electrode 17, and the likewere formed through the patterning process using the resist pattern filmand then a resist material droplet injected with an ink-jet device waslanded on the center between these electrodes to form the additionalresist pattern film and that using the additional resist pattern film asa mask, the semiconductor film was subjected to the patterning process.The present Embodiment is different from Embodiment 1 in that the resistpattern film on the source wiring 14, the source electrode 15, and thedrain electrode 17 and the like was removed, and then thereon a siliconnitride film serving as a passivation layer (passivation film) wasformed, and then the additional resist pattern film was formed.

Specifically, the production method of the TFT in the present Embodimentincludes, as shown in FIG. 23, the gate electrode-forming step 1, thegate insulating film and semiconductor film-forming step 2, the sourcemetal film and resist film-forming step 3, a source metal film andsemiconductor film-etching and passivation film-formation step 91, aresist film at channel-forming step 92, and a channel resist film and achannel-forming step 93. Among them, the gate electrode-forming step 1,the gate insulating film and semiconductor film-forming step 2, and thesource metal film and resist film-forming step 3 are the same as inEmbodiment 1, and therefore the explanation thereof is omitted.

FIG. 24( a) is a planar view schematically showing a TFT prepared inEmbodiment 3 and a configuration near the TFT, and FIG. 24( b) is across-sectional view schematically showing the configuration taken alongline R-R in FIG. 24( a).

The TFT 94 prepared in the present Embodiment and the TFT in Embodiment1 are the same in many respects, but they are different in that the TFT94 has a passivation layer 96 on a TFT channel 95, as shown in FIG. 24.The passivation layer 96 has an almost the same planar shape as of theTFT channel 95.

“Source Metal Film and Semiconductor Film-Etching and PassivationFilm-Forming Step 91”

In this step, a treatment of separating and removing the resist patternfilm 30 and formation of a silicon nitride (SiN_(x)) film 97 serving asa passivation layer 96 later were performed in addition to the sourcemetal film and semiconductor film-etching step 4 in Embodiment 1. FIG.25( a) is a planar view schematically showing a configuration aftercompletion of the source metal film and semiconductor film-etching andpassivation film-forming step 91; and FIG. 25( b) is a cross-sectionalview schematically showing the configuration taken along line S-S inFIG. 25( a).

The resist pattern film 30 was removed after the etching treatment forthe source metal film and the n⁺ type amorphous silicon film, as inEmbodiment 2. Then, the silicon nitride film 97 was formed on the entiresurface of the substrate. Then, as a surface treatment for thesubstrate, the surface was coated with a fluorinated alkylsilanesolution containing an alcohol as a main solvent and subjected to heattreatment at 100° C. After this surface treatment, the contact angle wasmeasured using the resist material. The surface had a contact angle of30° to 40°. As a result, the lyophilic or lyophobic property for theresist material could be provided, as in Embodiment 1 and the like.

The material of the passivation layer 96 is not especially limited tosilicon nitride. Instead of the silicon nitride film 97, inorganicmaterial films such as a silicon oxide film, organic material films, andthe like, may be used. Also in the surface treatment, a method otherthan the method in Embodiment 1 and the like may be used. Theabove-mentioned contact angle value is mentioned just as one example,and it is not especially limited in the present invention.

“Resist Film at Channel-Forming Step 92”

This step is mentioned with reference to FIG. 26. FIG. 26( a) is aplanar view schematically showing a configuration after completion ofthe resist film at channel-forming step 92; and FIG. 26( b) is across-sectional view showing the configuration taken along line T-T inFIG. 26( a).

In this step, as in Embodiment 1, the resist droplet was injected withthe ink-jet device to form an additional resist pattern film 99 at a TFTgap 98.

Also in the present Embodiment, the reason why the resist pattern film99 was formed to mainly fill the TFT gap 98 is the same as inEmbodiment 1. However, the present Embodiment is different fromEmbodiment 1 in that the unevenness formed by the multilayer structureof the source electrode 15 of the TFT gap 98, the drain electrode 17,and the n⁺ type amorphous silicon layer 13 on both sides serves as abank for saving the resist droplet. That is, in the present Embodiment,the silicon nitride film 97 is formed on the TFT channel 95, but thecontact angle at the bank part and that at other parts are the same.Accordingly, it is a function of the bank (unevenness) that is used forsaving the resist droplet.

Also in the present Embodiment, the shape of the resist droplet can becontrolled by using the bank pattern, that is, the bank patternincluding the opening at the both ends of the TFT gap (open end of thebank pattern) and the banks at the source electrode portion and thedrain electrode portion on the both sides of the TFT gap 98.

“Channel-Forming Step 93”

In this step, the substrate after completion of the above-mentionedresist film at channel-forming step 92 was subjected to a dry-etchingtreatment, and thereby the passivation layer 96 was obtained from thesilicon nitride film 97 and the amorphous silicon layer 12 was obtainedfrom the amorphous silicon film 27. In the dry etching treatment, carbontetrafluoride (CF₄) gas, oxygen (O₂) gas, and the like were used incombination as an etching gas. The resist pattern film 99 was used as amask to form the passivation layer 96, and the source wiring 14, thesource electrode 15, the drain connecting wiring 16, the drain electrode17, and the resist pattern film 99 were used as a mask to form theamorphous silicon layer 12. As a result, such a TFT basic structure asin FIG. 24 was obtained. The TFT channel 95 was formed in a region whichwas a lower layer of the TFT gap 98, in the amorphous silicon layer 12.The shape of the TFT channel 95 reflects the shape of the resist patternfilm 99. Further, the passivation layer 96 was formed on the amorphoussilicon layer 12.

As mentioned above, the present Embodiment is the same as Embodiment 1also in that the number of photolithography processes performed in thepresent Embodiment was two and the pattern formation device such as anink-jet device was used. Accordingly, in the present Embodiment as wellas Embodiment 1, the number of photolithography processes is reduced andadvantages such as reduction in material costs, environmental loads, andequipment investment costs in production of TFTs can be obtained. InEmbodiments 1 and 2, the step of forming the passivation film andpatterning it needs to be additionally performed. However, in thepresent Embodiment, these steps can be omitted because the patternedpassivation layer 96 was obtained.

The production method in the present Embodiment is the same as inEmbodiment 1 in that the source electrode 15 and the drain electrode 17were formed in first and that the bank pattern having an opening wasformed. Therefore, as in Embodiment 1, a thin film element such as a TFTcan be prepared through a smaller number of production steps incomparison to the conventional production method. Also with respect tocomparison with the conventional technology, the production method inthe present Embodiment is the same as in Embodiment 1.

Also in the present Embodiment, the shape of the resist pattern film 99and the surface treatment method in the source metal film andsemiconductor film-etching and passivation film-forming step 91 and thelike are not especially limited and may be variously changed as inEmbodiment 1.

Embodiment 4

A production method of an inverse stagger type amorphous silicon TFTaccording to Embodiment 4 is mentioned with reference to FIGS. 27 and28. In FIGS. 27 and 28, components having substantially the samefunction as in Embodiment 1 are expressed by the same symbol.

In the production method of the present Embodiment, an additional resistpattern film is formed in a region corresponding to a TFT channelbetween resist pattern films for forming a source wiring, a sourceelectrode, a drain electrode, and the like, using an ink-jet device.That is, without using a halftone exposure method, a resist pattern filmhaving portions with different film thicknesses is prepared in a regioncorresponding to a TFT channel. After the additional resist pattern filmis formed, steps like those in the halftone exposure method disclosed inthe above-mentioned Nonpatent Document 1 are performed to produce a TFT.

The production method of the TFT in the present Embodiment includes, asshown in FIG. 27, the gate electrode-forming step 1, the gate insulatingfilm and semiconductor film-forming step 2, the source metal film andresist film-forming step 3, a resist film at channel-forming step 101, asource metal film and semiconductor film-etching step 102, a resist filmat channel-removing step 103, and a channel-processing step 104. Amongthem, the gate electrode-forming step 1, the gate insulating film andsemiconductor film-forming step 2, and the source metal film and resistfilm-forming step 3 are the same as in Embodiment 1, and therefore theexplanation thereof is omitted. The TFT produced in the presentEmbodiment has almost the same shape as in the TFT produced inEmbodiment 1, shown in FIGS. 2( a) and (b).

“Resist Film at Channel-Forming Step 101”

In this step, a resist pattern film 106 was formed at a TFT gap 105.FIG. 28( a) is a planar view schematically showing a configuration aftercompletion of the resist film at channel-forming step 101; and FIG. 28(b) is a cross-sectional view schematically showing the configurationtaken along line U-U in FIG. 28( a).

Procedures in this step are mentioned below.

First, the substrate after the previous step (the source metal film andresist film-forming step 3) was subjected to a plasma surface treatmentusing oxygen (O₂) gas and carbon tetrafluoride (CF₄) gas to provide thesurfaces of the resist pattern film 30 and the source metal film 29,exposed on the substrate surface, with a lyophobic property for theresist droplet. The resist pattern film 30 had a contact angle of 40° to80°, and the source metal film 29 had a contact angle of 40° to 50°.That is, the lyophilic or lyophobic property for the resist materialcould be provided, as in Embodiment 1.

Then, using an ink-jet device, the resist droplet was added at the TFTgap 105 on the substrate after completion of this surface treatment. Asa result, the resist pattern film 106 was obtained. This resist patternfilm 106 had a shape shown in FIG. 28, because of the same reason as inEmbodiment 1. That is, the resist pattern film 106 having a thicknessthinner than that at other positions was formed at the TFT gap 105.

Materials other than the material for the resist pattern film 30 may beused as the material for the resist pattern film 106. For example, theresist pattern films 106 and 30 may be composed of different resins.This is performed for improvement in selectivity when only the resistpattern film 106 is removed later. The following steps are mentionedbelow simply, because the TFT is produced by the same steps as in thehalftone exposure method disclosed in Nonpatent Document 1.

“Source Metal Film and Semiconductor Film-Etching Step 102”

In this step, the source metal film 29, the n⁺ type amorphous siliconfilm 28, and the amorphous silicon film 27 were etched using the resistpattern film 30 and the additional resist pattern film 106 as a mask.Chlorine (Cl₂) gas, boron trichloride (BCl₃) gas, and the like were usedin combination as an etching gas.

“Resist Film at Channel-Removing Step 103”

In this step, the additional resist pattern film 106 was removed byashing and the like. At this time, the shape of the resist pattern film30 is deformed to have a slightly thinner line width by thinning, insome cases.

“Channel-Processing Step 104”

In this step, the source metal film 29 and the n⁺ type amorphous siliconfilm 28 at the TFT gap 105 from which the additional resist pattern film106 was removed were etched. Chlorine (Cl₂) gas, boron trichloride(BCl₃) gas, and the like were used in combination as an etching gas.

Until this step, each of the source metal film 29 and the n⁺ typeamorphous silicon film 28 was subjected to the two-step etchingtreatment in the present Embodiment.

Then, the resist pattern film 30 was removed. As a result, such a TFT asin FIGS. 2( a) and (b) was obtained.

In the present Embodiment, the resist pattern film having two differentfilm thicknesses was prepared without the halftone exposure method. Thatis, the halftone exposure method with low controllability in exposure,development, and the like can be replaced with one photolithographyprocess and the resist pattern film-forming step using the ink-jetmethod. Therefore, TFTs with uniform characteristics can be produced inthe substrate surface.

The production method of the present Embodiment is the same as that inEmbodiment 1 in that the bank pattern with an opening was used, but isdifferent in that the resist pattern film 30 on the both sides of theTFT gap 105 serves as a bank. Therefore, as in Embodiment 1, a thin filmelement such as a TFT can be prepared through a smaller number ofproduction steps in comparison to the conventional production method.Also with respect to comparison with the conventional technology, theproduction method in the present Embodiment is the same as in Embodiment1.

The present invention is not limited by the examples in the presentEmbodiment, such as the shape of the resist pattern film 106, thesurface treatment method in the resist film at channel-forming step 101,and may be variously changed, as in Embodiment 1.

Embodiment 5

A production method of an inverse stagger type amorphous silicon TFTaccording to Embodiment 5 is mentioned with reference to FIGS. 29 to 31.

In Embodiment 1, the source electrode and the drain electrode wereobtained, and then the resist material droplet was landed on the centerbetween these electrodes using the ink-jet device, and thereby anadditional resist pattern film was formed. In Embodiment 4, the resistpattern film for forming the source electrode and the drain electrodewas prepared, and then, using the ink-jet device, the resist materialdroplet was landed on the center between these electrodes. As a result,the additional resist pattern film was formed. Then, using thisadditional resist pattern film as a mask, the semiconductor films andthe like were processed.

In the present Embodiment, instead of the resist material, a droplet ofan organic solvent was injected and landed on the substrate, therebydeforming or dissolving the resist pattern film near the position atwhich the droplet was landed. As a result, the additional resist patternwas obtained.

This method may be applied to the production methods of Embodiment 1 andEmbodiment 4. The case where this method is applied to Embodiment 1 ismentioned in the present Embodiment.

The production method of the TFT according to the present Embodimentincludes the gate electrode-forming step 1, the gate insulating film andsemiconductor film-forming step 2, the source metal film and resistfilm-forming step 3, a source metal film and semiconductor film-etchingstep 111, a resist film at channel-forming step 112, and achannel-forming step 113, as shown in FIG. 29.

Among them, the gate electrode-forming step 1, the gate insulating filmand semiconductor film-forming step 2, and the source metal film andresist film-forming step 3 are the same as in Embodiment 1, andtherefore the explanation thereof is omitted. The TFT produced in thepresent Embodiment has almost the same shape as in the TFT produced inEmbodiment 1, shown in FIGS. 2( a) and (b).

“Source Metal Film and Semiconductor Film-Etching Step 111”

This step is the same as the source metal film and semiconductorfilm-etching step 4 in Embodiment 1. In the present Embodiment, however,the surface treatment finally performed in this step is performed insuch a way that the surface shows a proper lyophilic or lyophobicproperty for a droplet of an organic solvent used in the following step.In this Embodiment, a plasma treatment method using oxygen (O₂) gas andcarbon tetrafluoride (CF₄) gas was used to provide a specific lyophilicor lyophobic property for the surface. After this surface treatment, thelyophilic or lyophobic property was checked based on a contact angle.The resist pattern film 30 exposed on the substrate surface had acontact angle of 40° to 80°, and the amorphous silicon film 27 exposedthereon had a contact angle of 20° to 30°. As in Embodiment 1, the endsurfaces of the n⁺ amorphous silicon layer 13, the source electrode 15,and the drain electrode 17, each exposed on the TFT gap 31 side, mayhave a contact angle of 20° to 80°. This is estimated from the resultsobtained by subjecting the film surface made of the same material to thetreatment under the same conditions. In the present invention, however,the above-mentioned surface treatment is not especially limited to themethod in the present Embodiment. As mentioned below, a method offorming a film with a proper lyophilic or lyophobic property for thedroplet of the organic solvent and the like may be used. Theabove-mentioned contact angle value is also mentioned just as oneexample, and the present invention is not limited thereto.

“Resist Film at Channel-Forming Step 112”

In this step, one droplet of an organic solvent (solvent droplet) wasinjected into the vicinity of the center of the TFT gap 31 on the glasssubstrate 8 after the above-mentioned source metal film andsemiconductor film-etching step 111, using an ink-jet method. The shapeof this solvent droplet was changed with lapse of time, after landed onthe glass substrate 8.

The kind of the organic solvent was only diethylene glycol monomethylether. The volume of one droplet of the solvent was 1 to 2 pl. In thepresent invention, the organic solvent is not especially limited as longas it acts on the resist pattern film 30 and the like on the substrateand deforms or dissolves it. It is preferable that the volume of thesolvent droplet is appropriately determined depending on the form of theresist pattern film 30, the contact angle of the resist pattern film 30and the amorphous silicon film 27, the pattern of the additional resistpattern film to be formed by deforming or dissolving the resist patternfilm 30, and the like.

FIG. 30( a) is a planar view schematically showing a configuration aftercompletion of landing of the solvent droplet; and FIG. 30( b) is across-sectional view schematically showing the configuration taken alongline V-V in FIG. 30( a).

The solvent droplet 114 was deformed into a shape shown in FIGS. 30( a)and (b) a little while after landed. The droplet spread and filled theTFT gap 31, and its movement was stopped in the vicinity of the bothends 34 of the TFT gap 31.

Such a shape of the solvent droplet 114 was controlled and formed by thebank pattern, that is, the bank pattern constituted by the opening andthe bank, and the lyophilic or lyophobic property provided by thesurface treatment in the previous step (the source metal film andsemiconductor film-etching step 111).

The reason why the solvent droplet 114 spread and filled the TFT gap 31is that the unevenness formed by the multilayer structure of the resistpattern 30 on the both sides of the TFT gap 31, the source electrode 15,the drain electrode 17, and the n⁺ type amorphous silicon layer 13served as a bank for saving the solvent droplet 14 and that thelyophilic or lyophobic property on the surface of the resist patternfilm 30 was adjusted by the surface treatment in the previous step. Inthis case, it is preferable that the surface of the resist pattern film30 has a lyophobic property higher than that on the surface of theamorphous silicon film 27.

The reason why the spreading solvent droplet 114 was stopped in thevicinity of the both ends 34 of the TFT gap 31 is attributed to thesurface tension of the solvent droplet 114 and the lyophobic property onthe surface of the amorphous silicon film 27. When the solvent droplet114 flows out of the both ends 34 of the TFT gap 31, the surface area ofthe solvent droplet 114 rapidly increases, and such an increase in thesurface area increases a force to rapidly become smaller. Because ofthese reasons, the solvent droplet 114 remains inside the narrow TFT gap31. Such a shape of the solvent droplet 114 is appropriately controlledby other conditions such as an amount of the droplet and a viscosity ofthe resist droplet.

Thus, even if the solvent droplet 114 is used instead of the resistdroplet, the shape of the solvent droplet 114 can be controlled by thebank pattern constituted by the opening on the both sides 34 and thebank having a multilayer structure of the resist pattern film 30constituting the both sides of the TFT gap 31, the source electrode 15or the drain electrode 17, the n⁺ type amorphous silicon layer 13. Asmentioned below, the shape of the solvent droplet 114 in the presentEmbodiment is mentioned just as one example, and the solvent droplet 114may have such another shape as in Embodiment 1 and the like.

FIG. 31( a) is a planar view schematically showing a configuration inwhich a resist pattern film 115 is formed inside the TFT gap 31; andFIG. 31( b) is a cross-sectional view schematically showing theconfiguration taken along line W-W in FIG. 31( a).

The organic solvent contained in the solvent droplet 114 gets contactwith a portion of the resist pattern film 30, and acts on and dissolvesthe portion, and then absorbs the resist material. Then, the organicsolvent is volatilized. In such a way, the resist pattern film 115 wasobtained.

In the present Embodiment, the organic solvent was volatilized bynatural drying, and then the entire substrate was subjected to heattreatment at 120° C. for improvement in resistance for a dry-etchingtreatment performed in the following step.

The present invention is not limited to this, and a method ofvolatilizing the organic solvent by heating the substrate and the likemay be used depending on the kind of the contained organic solvent andthe volume of the added solvent droplet 114. Various methods may be usedas a method of heating the substrate. The resist pattern film 30 wasdeformed into a shape of a resist pattern film 116 and had a deformedpart on each side of the TFT gap 31.

In this case, due to the volume shrinkage at the time of volatilizationof the organic solvent, the inside of the solvent droplet 114 becametemporarily negative pressure state, and part of the solvent droplet114, which flowed out of the both ends 34 of the TFT gap 31, could beabsorbed. Because of this function, the shape of the TFT gap 31 tends tohave a certain shape shown in FIGS. 31( a) and 31(b) regardless ofvariation in conditions such as a contact angle.

“Channel-Forming Step 113”

In this step, the substrate after subjected to the previous step (resistfilm at channel-forming step 112) was subjected to a dry-etchingtreatment, and thereby the amorphous silicon layer 12 was obtained fromthe amorphous silicon film 27. Chlorine (Cl₂) gas was used as an etchinggas and the resist pattern films 115 and 116 were used as a mask in thedry-etching treatment for the amorphous silicon film 27. As a result, aTFT basic structure shown in FIGS. 2( a) and (b) was obtained. The TFTchannel was formed at a portion corresponding to the TFT gap 31, in theamorphous silicon layer 12. The shape of the TFT channel reflects theshape of the resist pattern film 115.

The number of photolithography processes performed until the TFT basicstructure was obtained was two in the present Embodiment. However, inthe present Embodiment, the step of forming the additional resistpattern film 115 using the pattern formation device such as an ink-jetdevice was additionally performed.

The present Embodiment is also the same as Embodiment 1 in that thesource electrode 15 and the drain electrode 17 were formed in first andthat the bank pattern having an opening was formed. Thus, the use of thebank pattern having an opening permits such a process method as in thepresent Embodiment, in which a pair of electrodes such as a sourceelectrode and a drain electrode in a TFT are formed in the same planeand a solvent droplet is added at a position corresponding to a spacebetween the electrodes, and therefore a thin film element such as a TFTcan be prepared through a smaller number of production steps incomparison to the conventional production method. Also with respect tocomparison with the conventional technology, the production method inthe present Embodiment is the same as in Embodiment 1.

The production method in the present Embodiment is the same as that inEmbodiment 1 in that the source electrode 15 and the drain electrode 17were formed in first and that the bank pattern having an opening wasformed. Therefore, as in Embodiment 1, a thin film element such as a TFTcan be prepared through a smaller number of production steps incomparison to the conventional production method. Also with respect tocomparison with the conventional technology, the production method inthe present Embodiment is the same as in Embodiment 1.

The present invention is not limited by the examples in the presentEmbodiment, such as the shape of the resist pattern films 115 and 116,the surface treatment method in the source metal film and semiconductorfilm-etching step 111, and may be variously changed, as in Embodiment 1.

Embodiment 6

An Embodiment in which an inverse stagger type amorphous silicon TFT wasprepared is mentioned below with reference to FIGS. 32 to 35 as anEmbodiment of the present invention.

In Embodiments 1, 2, 3, and 5, the source electrode and the drainelectrode were obtained in first, and then a droplet of the resistmaterial or the organic solvent was landed on the center of theseelectrodes, thereby forming the additional resist pattern film. In thepresent Embodiment, in addition to this step of forming the additionalresist pattern film, a back surface exposure and a development treatmentusing the gate electrode shape were additionally performed. Thus, a TFTwas prepared by a method for forming a more excellent TFT channel shape.

The production method of the TFT in the present Embodiment is a methodincluding the above-mentioned back surface exposure and developmenttreatment in addition to the method shown in Embodiment 1. As shown inFIG. 32, for example, the production method includes the gateelectrode-forming step 1, the gate insulating film and semiconductorfilm-forming step 2, the source metal film and resist film-forming step3, the source metal film and semiconductor film-etching step 4, a resistfilm at channel-forming step 301, and the channel-forming step 6. In thepresent Embodiment, the above-mentioned back surface exposure anddevelopment treatment are added in the resist film at channel-formingstep 301.

FIG. 33( a) is a planar view schematically showing a configuration of aTFT 302 prepared in the present Embodiment; and FIG. 33( b) is across-sectional view schematically showing the configuration taken alongline AF-AF in FIG. 33( a).

The TFT 302 prepared in the present Embodiment has a bottom gatestructure, as shown in FIG. 33, and has a configuration in which a gateelectrode 303 branched from the gate wiring 9, the gate insulating film11, the amorphous silicon layer 12, the n⁺ type amorphous silicon layer13, the source electrode 15 branched from the source wiring 14, thedrain electrode 17 connected to the drain connecting wiring 16 arestacked on the glass substrate 8. A TFT channel 304 was formed in alower layer region at the space formed between the source electrode 15and the drain electrode 17, in the amorphous silicon layer 12. The shapein the vicinity of both ends 305 of the TFT channel 304 is formedthrough the back surface exposure and the development treatment, and itis a linear shape, in reflection of the shape of the gate electrode 303.

The production method of the TFT 302 in the present Embodiment ismentioned below. The present Embodiment is different form Embodiment 1only in the resist film at channel-forming step 301, and therefore thisstep is mentioned.

The resist film at channel-forming step 301 of the present Embodimentincludes a back surface exposure and a development treatment using thegate electrode shape, in addition to the resist film at channel-formingstep 5 in Embodiment 1. FIG. 34( a) shows a configuration on thesubstrate immediately after subjected to the back surface exposure. FIG.34( a) is a schematic planar view and FIG. 34( b) is a cross-sectionalview schematically showing the configuration taken along line AG-AG inFIG. 34( a). In FIG. 34( a), a region 306 exposed to diffracted lightdue to back surface exposure in the vicinity of the TFT channel 31before being formed, is shown by the shaded region. In the presentEmbodiment, a resist material having photosensitivity was used as amaterial for the resist pattern film 35. Specifically, a material mainlyincluding novolak resin, a photosensitive agent, and diethylene glycolmonobutyl ether was used. Therefore, the resist pattern film 35 at theregion 306 was exposed. The method of the back surface exposure wasperformed by irradiating the substrate with light from the back surface,using a back surface exposure device including an extra high pressuremercury lamp.

Then, the development treatment was performed, and then a substrateshown in FIGS. 35( a) and (b) was obtained. FIG. 35( a) is a schematicplanar view and FIG. 35( b) is a cross sectional view schematicallyshowing the configuration taken along line AG-AG in FIG. 35( a). Theportion exposed by the back surface exposure of the resist pattern film35 was dissolved, and thereby a shaped resist pattern film 307 wasobtained at the TFT gap 31. An aqueous solution of TMAH (tetramethylammonium hydroxide) was used for this development. The preparationconditions of the resist pattern film 30 such as a material and a heattreatment were appropriately determined so as not to be substantiallyinfluenced by the development treatment.

A resist pattern film 307 is sandwiched between the source electrode 15and the drain electrode 17, and the shape at portions not surrounded bythese electrodes is determined by the shape of the gate electrode 303.The source electrode 15, the drain electrode 17, and the gate electrode303 are prepared by the photolithography process with accuracy, andtherefore, the resist pattern film 307 also has a shape with highaccuracy equivalent to that in photolithography. Therefore, thetreatment in the following channel-forming step 6 is performed, and aTFT channel 304 with high accuracy can be formed. As a result, thedisplay quality is not reduced even if a plurality of such TFTs isformed on an active matrix substrate for display devices, for example.

Thus, the production method in the present Embodiment is especiallyuseful because the shape in the vicinity of the both ends 305 of the TFTchannel 304 can be controlled by the back surface exposure and thedevelopment treatment with accuracy equivalent to that inphotolithography.

The addition of the back surface exposure and the development treatmentin the present Embodiment is especially useful in the combination ofEmbodiments 1 to 3 and 5, but may be performed in combination with themethod in other Embodiments of the present invention. The presentinvention is not especially limited to the examples used in the presentEmbodiment, and may be variously changed, as in other Embodiments andthe like.

Embodiment 7

The production methods of the TFT in the present invention are mentionedin Embodiments 1 to 6, but in Embodiment 7, a shape of a TFT suitablefor such production methods is mentioned with reference to FIGS. 36-1and 36-2. In FIGS. 36-1 and 36-2, components having substantially thesame function as in Embodiment 1 are expressed by the same symbol.

FIG. 36-1( a) is a planar view schematically showing a configuration ofa TFT in Embodiment 7, and FIG. 36-1( b) is a cross-sectional viewschematically showing the configuration taken along line X-X in FIG.36-1( a).

The TFT 121 in the present Embodiment has a bottom gate structure, asshown in FIGS. 36-1( a) and (b), and has a configuration in which thegate electrode 10 branched from the gate wiring 9, the gate insulatingfilm 11 that is an upper layer of the gate electrode 10, the amorphoussilicon layer 12, the n⁺ type amorphous silicon layer 13, the sourceelectrode 15 branched from the source wiring 14, a drain electrode 122connected to the drain connecting wiring 16 are stacked on the glasssubstrate 8. The TFT 121 has semiconductor layers (the amorphous siliconlayer 12 and the n⁺ type amorphous silicon layer 13) on the entiresurface on the substrate side of the source electrode 15, the drainelectrode 122, and the source wiring 14 connected to the sourceelectrode 15, and also has a partial notch 122 a at the end on the TFTchannel 18 side of the drain electrode 122.

The TFT channel 18 was formed in a lower layer region at the spaceformed between the source electrode 15 and the drain electrode 122, inthe amorphous silicon layer 12. The drain connecting wiring 16 is formedfor connecting a pixel electrode (not shown) and the drain electrode 122in a display application, for example. On the upper side of the sourceelectrode and the drain electrode in a commonly used TFT such as the TFTaccording to the present Embodiment, a passivation film is often formedto cover the TFT channel, which is not shown in the present Embodiment.

The TFT 121 shown in FIGS. 36-1( a) and (b) has the notch 122 a near thecenter of the drain electrode 122. The notch 122 a is also formed on thestructure in which the gate electrode 10, the gate insulating film 11,and the amorphous silicon film 12 are stacked on the glass substrate 8,and therefore can function as a channel of the TFT 121.

The notch 122 a shown in FIG. 36-1( a) had a depth Wa of 5 μm, and awidth Wb of 10 μm. In FIG. 36-1( a), L was 3 μm, and W was 60 μm.

The reason why such a notch 122 a was formed in the present Embodimentis mentioned below.

The production method in Embodiment 1 is assumed to be used as theproduction method of the TFT 121 in the present Embodiment.

According to the production method in Embodiment 1, the additionalresist pattern film 35 was formed at the TFT gap 31 in the resist filmat channel-forming step 5. At this time, the resist pattern film 35 isprepared by landing the resist droplet on the substrate using theink-jet device as mentioned in Embodiment 1. The resist droplet spreadsand fills the TFT gap 31.

The volume of the resist droplet with which the TFT gap 31 is justfilled was calculated. That is, the volume, at which the unevennessformed by the multilayer of the n⁺ type amorphous silicon layer 13, thesource electrode 15 or the drain electrode 17, and the resist patternfilm 30 is filled at the space between the source electrode 15 and thedrain electrode 17, was calculated. As a result of calculation based onthe values described in Embodiment 1, the volume of the TFT gap 31 was0.54 pl.

Therefore, if the production method in Embodiment 1 is used, a propervolume of the resist droplet is determined on the basis of 0.54 pl. Ifthe volume is much larger than 0.54 pl, the surface tension exceeds thelimit at the both ends 34, and a large amount of the resist dropletflows out of the both ends 34 at the TFT gap 31.

The minimum volume of the droplet injectable by the ink-jet device isgenerally about 1 pl or more. The volume of the resist droplet injectedin Embodiment 1 was 1 to 2 pl. This depends on the head structure andthe like of the ink-jet device. That is, the smaller the liquid dropletis, the smaller the nozzle (hole for injection) diameter is. Therefore,higher process accuracy is needed or nozzle clogging is easily caused.

Accordingly, the minimum volume of the droplet injectable by the ink-jetdevice is more than twice as large as the above-calculated volume of theTFT gap 31.

In order to reduce the difference between the two, it is preferable thatat least one of the source electrode and the drain electrode is providedwith a notch, as in the present Embodiment. Thus, the notch can beformed as a position where an excess amount of the droplet is absorbedin the resist film at channel-forming step 5.

In the TFT 121 in the present Embodiment, the drain electrode 122 wasprovided with the notch 122 a. Therefore, the volume of the TFT gap 31could be adjusted to be 0.69 pl, which is closer to the volume of theresist droplet. Therefore, it can be possible to prevent a large amountof the resist droplet from flowing out of the both ends 34 in the resistfilm at channel-forming step 5, and therefore, the shape of the TFT 121can be more stably formed.

The present inventors found that the above-mentioned functional effectscould be observed through experiments using patterns having a notch andthose not having a notch, and that it is effective to provide the sourceelectrode and/or the drain electrode with the notch. The notch formationin the drain electrode slightly reduces a value of on-state current ofTFTs, but it can be possible to redesign the TFTs to have desiredelectric properties by optimization such as review of the entire size.

As mentioned above, if a TFT is produced by the production method inEmbodiment 1, at least one of the source electrode and the drainelectrode is provided with a partial notch at the end on the channelside, and thereby the difference between the volume of the TFT channeland the minimum volume of the droplet injectable by the ink-jet devicecan be reduced and the shape of the TFT can be stably formed. Theproduction method is not limited to the production method in Embodiment1, and the same functional effects can be obtained even if theproduction methods in Embodiments 2 to 6 are used.

The TFT 121 in the present Embodiment has semiconductor layers (theamorphous silicon layer 12 and the n⁺ type amorphous silicon layer 13)on the entire surface on the substrate side of the source electrode 15,the drain electrode 122, and the source wiring 14 connected to thesource electrode 15, and can be produced by the production methods inEmbodiments 1 to 6 of the present invention.

Accordingly, the number of photolithography processes can be easilyreduced if the TFT 121 is produced by the production methods ofEmbodiments 1 to 6.

The shape of the notch 122 a may be a shape shown in FIGS. 36-2( a) and36-2(b). FIG. 36-2( a) is a planer view schematically showing anotherexample of the TFT configuration in Embodiment 7; and FIG. 36-2( b) is across-sectional view schematically showing the configuration taken alongline Y-Y in FIG. 36-2( a).

In the TFT 123 shown in FIG. 36-2, the drain electrode 124 had a notch124 a, and the length Wa was 5 μm and the width Wb was 3 μm. The widthWb was set to be the same as the channel length L of the TFT. Aplurality of the notches 124 a may be formed.

Embodiment 8

The TFT in the present invention may be a TFT including a semiconductorlayer on the entire surface side of a source electrode, a drainelectrode, and a source wiring connected to the source electrode,wherein the TFT has a channel having a square U-shape or a U-shape. Thepresent Embodiment shows a TFT according to such an embodiment.

A TFT 125 having such a shape as in FIGS. 37( a) and (b) may bementioned as the above-mentioned TFT, for example. FIG. 37( a) is aplanar view schematically showing the TFT 125; and FIG. 37( b) is across-sectional view schematically showing the TFT 125 taken along lineZ-Z in FIG. 37( a). The TFT 125 shown in FIG. 37 has a bottom gatestructure as in the TFT produced in other Embodiments. Thecharacteristics of the TFT 125 are that the TFT channel 18 has a squareU-shape (U-shape) and has a shape bent at two points. Similarly, a drainelectrode 126 also has a square U-shape, but a source electrode 127 hasa linear shape. The TFT channel 18 has a square U-shape, and thereforeit is within a smaller circle in comparison to the channel having alinear shape.

Such a shape of the TFT 125 is suitable for the processes of the presentinvention, mentioned in Embodiments 1 to 6. This is because the resistdroplet immediately after landed on the substrate has an almost circularplaner shape in the resist film at channel-forming step (for example,the step 5) in the middle of the preparation of the TFT 125. If theshape of the TFT channel 18 is formed to be within a small circle, theresist droplet can fill the TFT gap as much as possible immediatelyafter landed. Therefore, a TFT having a substantially long channel widthcan be produced even if the resist droplet after landed is not soextended. Therefore, such a shape is useful if a TFT having a longchannel is produced by the method of the present invention. Further, itcan be possible to increase a proportion of the channel area to the areaof the portion constituting the semiconductor element in thesemiconductor layer and therefore the volume of the channel groove orthe resist groove can be increased. As a result, the fluid materialadded dropwise in the channel groove or the resist groove can be easilykept inside the groove, and the resist pattern film can be formed withaccuracy. In addition, the TFT 125 can be produced by the methods inEmbodiments 1 to 6 of the present invention, because the TFT 125 hassemiconductor layers (the amorphous silicon layer 12 and the n⁺ typeamorphous silicon layer 13) on the entire surface on the substrate sideof the source electrode 127, the drain electrode 126, and the sourcewiring 14 connected to the source electrode 127. Therefore, the use ofthe production methods in Embodiments 1 to 6 permits easy production ofthe TFT 125 having a long channel and easily reduces the number ofphotolithography processes.

An allowable landing error of the ink-jet device in the case where theTFT 125 is produced by the production method shown in Embodiment 1 waschecked for reference.

First, the detailed shape of the source electrode 127 and the drainelectrode 126 is mentioned with reference to FIG. 38. FIG. 38 is anenlarged planar view schematically showing the source electrode 127 andthe drain electrode 126 in FIG. 37( a). In FIG. 38, a distance L betweenthe source electrode 127 and the drain electrode 126 was 3 μm, and withrespect to the size of the source electrode 127 and the drain electrode126, W1 was 30 μm; W2 was 11 μm; W3 was 40 μm; and W4 was 43 μm. Theentire TFT 125 has an almost square shape because the values of W3 andW4 are close to each other and the TFT channel is formed at the TFT gap31 that is a space between the source electrode 127 and the drainelectrode 126. The effective channel width W of the TFT is unclear, butmay be 59 to 71 μm in consideration of each length of at the end on thechannel side of the source electrode 127 and the drain electrode 126.The TFT 7 in Embodiment 1 had a channel width W of 60 μm, which is avalue close to this range.

The same method as in Experimental Example 1 was used as an experimentalmethod. In the resist film at channel-forming step 5 that is in themiddle of preparation of the TFT 125, a resist droplet was intentionallylanded at a position away from the center of the TFT gap 31 shown by x.The observation method and the criterion were the same as inEmbodiment 1. The following Table 2 shows the results.

TABLE 2

Each of the X-coordinate and the Y-coordinate in Table 2 represents adistance from the center of the TFT gap 31, and its unit is micrometer.The directions of the X-axis and the Y-axis are those shown in FIG. 38,respectively. As shown in Table 2, in the present Embodiment, allpattern films which showed an X coordinate of −9 to +9 μm and aY-coordinate of −9 to +6 μm were estimated as “good”. Also in the TFT125 in the present Embodiment, the allowable landing error of theink-jet device could be reduced.

In the present invention, the embodiment shown in the present Embodimentin which the channel has a square U-shape or a U-shape and theembodiment shown in Embodiment 7 in which at least one of the sourceelectrode and the drain electrode has a notch may be employed incombination, and both effects can be obtained. A TFT 128 is shown inFIGS. 39( a) and (b) as one example. FIG. 39( a) is a schematic planarview; and FIG. 39( b) is a cross-sectional view schematically showingthe TFT 128 taken along line AA-AA in FIG. 39( a). The TFT 128 has aU-shaped TFT channel 18, and includes a drain electrode 129 having twonotches 129 a and 129 b. Each of the notches 129 a and 129 b has a Wa of5 μm and Wb of 3 μm.

FIGS. 40 (a) and (b) show similar examples. FIG. 40( a) is a schematicplanar view; and FIG. 40( b) is a cross-sectional view schematicallyshowing a TFT 131 taken along line AB-AB in FIG. 40( a). The TFT 131 inthese figures includes a source electrode 133 and a drain electrode 132having a notch 132 a. The notch 132 a has a Wa of 5 μm and Wb of 11 μm.In the TFT 131 shown in FIG. 40, the portion where the channel length ofthe TFT is partially enlarged is a portion where the notch 132 a isformed.

Embodiment 9

The TFT in the present invention is a TFT having a semiconductor layeron the entire surface on the substrate side of a source electrode, adrain electrode, and a source wiring connected to the source electrode,wherein the source electrode and the drain electrode has corners nearthe ends of the TFT channel. The present invention relates to a TFTaccording to such an embodiment.

The TFT in the present Embodiment may have the same embodiment as in theTFT 7 shown in FIGS. 2( a) and (b).

FIG. 41( a) is a planar view schematically showing the source electrode15 and the like partially extracted from FIG. 2( a). In FIG. 41( a), thesource electrode 15 and the drain electrode 17 have corners 143, 144,145, and 146 near ends 141 and 142 of the TFT channel 18. As a result ofa wholehearted examination, the present inventors found that such a TFTin which the source electrode and the drain electrode have corners nearevery end of the TFT channel as shown in FIG. 41( a) is preferable, andthat the shape of the TFT channel can be stabilized particularly if thecorner has an angle of 90°.

This could be identified by preparing a TFT 147 shown in FIG. 41( b) forcomparison by the method in Embodiment 1, and comparing it with theconfiguration in FIG. 41( a), for example. FIG. 41( b) is a planar viewschematically showing a source electrode 149 and the like of the TFT,which is partially extracted. In FIG. 41( b), the TFT 147 includes asource electrode 149 connected to a source wiring 148, a drain electrode151 connected to a drain connecting wiring 150, and a TFT channel 152made of an amorphous silicon film formed between the source electrode149 and the drain electrode 151. In the vicinity of an end 153 of theTFT channel 15, the source electrode 149 and the drain electrode 151include the corners 155 and 156. In the vicinity of the other end 154,only the source electrode 149 has a corner 157, and the drain electrode151 is connected to the drain connecting wiring 150 to have a linearshape and therefore has no corner.

According to the results of the preparation of this TFT 147 by themethods shown in Embodiments 1 to 6, as shown in FIG. 41( b), at the end154 of the TFT channel 152, the TFT channel 152 often had such a contourthat extends to the drain connecting wiring 150 side, and the shapevaried among a plurality of TFTs and tended to be deformed in comparisonto the shape at the end 153.

This may be attributed to behavior of the resist droplet in the resistfilm at channel-forming step, and may be because of difference when theresist droplet which slightly flowed out of the ends 153 and 154 isretreated by drying of the organic solvent, particularly. That is, atthe end 153, the source electrode 149 and the drain electrode 151 havethe corners 155 and 156, and therefore the bank formed by these cornersalso has corners. Therefore, the contour of the resist droplet isretreated to the line connecting these two corners 155 and 156. On theother hand, at the end 154, there is no corner on the drain electrode151 side, and therefore, a point where the contour of the resist dropletis retreated is hard to determine. The shape of the TFT channel 152 isdetermined by the contour after the resist droplet is retreated, andtherefore it would appear that the shape at the end 154 is hardlydetermined.

In a TFT in which the source electrode and the drain electrode havecorners near every end of the TFT channel, like a TFT shown in FIG. 41(a), the shape at the both ends of the TFT channel was stabilized.

As mentioned above, such a TFT in which the source electrode and thedrain electrode have corners near every end of the TFT channel as in thepresent Embodiment is preferable if the methods mentioned in Embodiments1 to 6 are used to produce TFTs. Particularly if the corner has an angleof 90° or less, the shape of the TFT is stabilized.

The present Embodiment is mentioned using the production method of theTFT mentioned in Embodiment 1 as an example, but the same results can beobtained if the production methods in Embodiments 2 to 6 are used.

The embodiment in which the channel has a square U-shape or a U-shape,shown in Embodiment 8, and the embodiment in the present Embodiment canbe employed in combination, which is effective because both effects canbe obtained. A TFT 158 in such an embodiment is shown in FIGS. 42( a)and (b), as an example. FIG. 42( a) is a schematic planar view; and FIG.42( b) is a schematic cross-sectional view of the TFT 158 taken alongline AC-AC in FIG. 42( a). The TFT 158 has a U-shaped TFT channel 159inside a region 160 in FIG. 42( a).

Embodiment 10

The TFTs and the production methods thereof shown in Embodiments 1 to 9can be applied to a diode having the same internal structure as in theseTFTs. The present Embodiment relates to a diode according to such anembodiment.

A diode having a structure shown in FIGS. 43( a) and (b) may bementioned as the above-mentioned diode. FIG. 43( a) is a planar viewschematically showing the diode in the present Embodiment and theconfiguration near the diode. FIG. 43( b) shows a cross-sectional viewschematically showing the configuration taken along line AD-AD in FIG.43( a).

A diode 171 in the present Embodiment has a bottom gate structure andhas a configuration in which a gate electrode 173, a gate insulatingfilm 174, an amorphous silicon layer 175, an n⁺ type amorphous siliconlayer 176, a drain electrode 178 connected to a connecting wiring 177, asource electrode 180 connected to a connecting wiring 179, a passivationfilm 181, a conductive film for connection 182 are stacked on a glasssubstrate 172. Between the drain electrode 178 and the source electrode180, part of the amorphous silicon layer forms a channel 183, and suchcomponents and the gate electrode 173 and the like constitutes a TFTpart 185 having the same structure as in a TFT. A contact part 184 isformed at a portion of the connecting wiring 179. At the contact part184, the gate insulating film 174 and the passivation film 181 areopened, and mainly over this opening, the conductive film for connection182 is formed as an upper layer, and the gate electrode 173, theconnecting wiring 179, and the source electrode 180 are electricallyconnected.

The passivation film 181 is made of silicon nitride, and the conductivefilm for connection 182 is made of ITO (indium tin oxide). Othercomponents are constituted as shown in Embodiment 1.

The diode 171 in the present Embodiment is formed to connect arbitrarywirings such as adjacent source wirings, gate wirings and the like in anactive matrix substrate, for example. Its purpose is to prevent staticelectricity from burning elements such as TFT or wirings in thesubstrate. For example, if static electricity is accumulated on a wiringand the wiring has a potential much higher than surrounding potential,the source electrode 180 and the gate electrode 173 of the diode 171electrically connected to the wiring, also have a high potential and theTFT part 185 is in ON-state to be in the conductive state. Therefore,the static electricity on this wiring can be flowed through the drainelectrode 178 and the connecting wiring 177. Accordingly, theabove-mentioned burning and the like can be prevented. If staticelectricity is not accumulated, the TFT part 185 is not in ON-state andhas a high resistance. Therefore, the wirings and the like can besubstantially electrically separated.

The diode 171 is prepared by additionally performing a step of formingthe passivation film 181 and a step of preparing the conductive film forconnection 182 after the production method in Embodiment 1, and can beprepared by forming films constituting these films 181 and 182 over theentire surface of the substrate and patterning the films byphotolithography. The silicon nitride forming the passivation film 181was prepared by a plasma enhanced CVD method, and the conductive filmfor connection 182 was prepared by a sputtering method.

As mentioned above, the TFT part 185 is prepared by the method inEmbodiment 1, and therefore the channel 183 reflects the shape of theresist pattern film formed by the droplet of the resist material (resistdroplet) injected with the ink-jet device. The reason why this channel183 did not have a circular shape is because the bank formed by thedrain electrode 178, the source electrode 180, and the like controlledthe direction where the resist droplet was wet and spread and becausethe resist droplet could be gathered between the drain electrode 178 andthe source electrode 180 when the organic solvent in the resist dropletwas volatilized.

As shown in the present Embodiment, the production methods of the TFTsin Embodiments 1 to 6 can be applied to a diode having such a structureas in these TFT structures. The present Embodiment as well asEmbodiments 1 to 6 attributes to reduction in the number ofphotolithography processes. Therefore, the same production merits can beobtained.

The shape of the diode and the configuration of the electrode are notlimited to the examples in FIG. 43. A diode 186 shown in FIGS. 44( a)and (b) may be used. FIG. 44( a) is a schematic planar view; and FIG.44( b) is a cross-sectional view schematically showing the diode 186taken along line AE-AE in FIG. 44( a). In a contact part 187, the gateelectrode 173 and the connecting wiring 179 are not connected to eachother. Instead, a conductive film for connection 188 is connected to theconnecting wiring 179 and covers the entire TFT part 189, therebyserving as a gate electrode of the TFT to function as a diode. A diodewhich has the characteristics of the diode shown in FIGS. 43 and 44 maybe used. In this case, both of the gate electrode and the conductivefilm for connection serve as a gate electrode of the TFT.

An embodiment in which a transparent electrode for display is formedusing the conductive film for connection 182 or 188 in the presentEmbodiment may be employed.

Embodiment 11

The active matrix substrate (circuit substrate) in the presentEmbodiment is a TFT array substrate and has an embodiment shown in FIG.45-1. FIG. 45-1 is a planar view schematically showing a configurationof the active matrix substrate in Embodiment 11.

An active matrix substrate 191 in the present Embodiment includes asource wiring 192, a gate wiring 193, and a TFT 194 that is a kind ofsemiconductor element, disposed at an intersection of these wirings. Aplurality of the TFTs 194 is formed in the active matrix substrate 191,and the substrate includes an effective region 195 used as a region forimage display or imaging and a peripheral region 196 positioned outsideof the effective region. The peripheral region 196 is a region wherewirings for driving the active matrix substrate 191, terminals (notshown) for connection to an external substrate, and the like aredisposed. In the active matrix substrate 191, a diode 197 that is a kindof semiconductor element is disposed in the peripheral region 196.

The TFT 194 is connected to a pixel electrode (not shown) for performingimage display and the like, the source wiring 192 and the gate wiring193, and has a shape shown in Embodiment 1. The diode 197 connectsadjacent gate wirings 193 and serves as a protection element forpreventing static electricity from burning wirings or elements, and hasa shape shown in Embodiment 10. The production methods mentioned inEmbodiments 1 to 6 and 10 may be used as a production method for thesecomponents. In this case, each of the TFT 194 and the diode 197 in thepresent Embodiment includes semiconductor layers (amorphous siliconlayer and n⁺ type amorphous silicon layer) on the entire surface on thesubstrate side of the source electrode, the drain electrode, and thesource wiring connected to the source electrode.

The characteristics of the active matrix substrate 191 in the presentEmbodiments are that the TFT 194 and the diode 197 are on a group ofequally spaced straight lines (a group of parallel lines) 198 in thegate wiring direction. The TFT 194 is a semiconductor element inside theeffective region 195 and the diode 197 is a semiconductor element insidethe peripheral region 196. The characteristics of the substrate 191 arethat such semiconductor elements which are positioned in differentregions and formed for different purposes are disposed on the samestraight line.

When the TFT 194 and the diode 197 were prepared, an ink-jet device wasused as a pattern formation device capable of selectively injecting oradding a resist material and the like as a liquid droplet at a positionon a substrate surface.

The ink-jet device includes an ink-jet head and injects a droplet of aresist material and the like while changing a relative position betweenthe ink-jet head and the substrate. When viewed from the substrate side,the ink-jet head generally moves in such a manner that scanning in onedirection in the plane is repeated, and during each scanning, theink-jet head is moved just by a specific distance in the directionperpendicular to the scanning direction. At this time, the number of thescanning is reduced as much as possible in order to perform thetreatment for the substrate efficiently.

In addition, nozzles for injecting the droplet are disposed equallyspaced in the ink-jet head. Therefore, the droplet can not be injectedon the substrate region positioned between the nozzles. Through onescanning, the droplet can be added only at the position on the group ofequally spaced straight lines through which nozzles are passed.Therefore, in order to minimize the number of the scanning, it ispreferable that the positions on which the droplet and the like islanded, that is, the positions where the semiconductor element is formedare on the group of equally spaced straight lines as much as possible.

Because of such a reason, the arrangement of the TFT 194 and the diode197 in the present Embodiment is suitable for the production methods ofthe TFT in Embodiments 1 to 6 and the production method of the diode inEmbodiment 10, and can reduce the number of the scanning of the ink-jethead, which makes it possible to perform the treatment for the substrateefficiently. In the present Embodiment, semiconductor elements such as aTFT and a diode other than the TFT 194 and the diode 197 may be disposedat least one of the effective region 195 and the peripheral region 196on the active matrix substrate 191, which is not shown in the figure. Inaddition, not every semiconductor element may be disposed on the groupof equally spaced straight lines.

An active matrix substrate 202 including TFTs 199 and diodes 200positioned on the group of equally spaced straight lines 201 in thesource direction may be used as an Modified Embodiment of the presentEmbodiment, as shown in FIG. 45-2. FIG. 45-2 is a planar viewschematically showing a configuration of the active matrix substrate 202according to Modified Embodiment of the present Embodiment.Semiconductor elements such as a TFT and a diode other than the TFT 199and the diode 200 may be disposed at one of the effective region 195 andthe peripheral region 196 on the active matrix substrate 202, which isnot shown in FIG. 45-2. If the methods mentioned in Embodiments 1 to 6and 10 are employed, the TFT 199 and the diode 200 include semiconductorlayers (amorphous silicon layer and n⁺ type amorphous silicon layer) onthe entire surface on the substrate side of the source electrode, thedrain electrode, and the source wiring connected to the sourceelectrode.

It is preferable that the scanning is performed in the gate wiringdirection when the ink-jet head is viewed from the substrate side,because a distance between gate wirings is larger than that betweensource wirings in an active matrix substrate commonly used in a liquidcrystal display device. This is because the distance between nozzlesformed in the ink-jet head can be made larger and therefore the numberof the nozzles is reduced and the process accuracy and the uniformity ofthe droplet landing distribution among the nozzles can be maintained.

In the present invention, the active matrix substrate may be an activematrix substrate in which more than one semiconductor element isdisposed at every intersection of the gate wiring with the source wiringin the effective region, and the more than one semiconductor element isdisposed on one group of equally spaced straight lines.

For example, as shown in FIG. 45-3, an active matrix substrate 207 inwhich TFTs 203 and 204 and diodes 205 are disposed on a group of equallyspaced straight lines 206 in the gate wiring direction may be used. FIG.45-3 is a planar view schematically showing a configuration of theactive matrix substrate 207 according to Modified Embodiment of thepresent Embodiment. Semiconductor elements such as a TFT and a diodeother than the TFTs 203 and 204, and the diode 205 may be disposed atleast one of the effective region 195 and the peripheral region 196 onthe active matrix substrate 207, which is not shown in FIG. 45-3. If themethods mentioned in Embodiments 1 to 6 and 10 are used, the TFTs 203and 204 and the diode 205 have semiconductor layers (amorphous siliconlayer and n⁺ type amorphous silicon layer) on the entire surface on thesubstrate side of the source electrode, the drain electrode, and thesource wiring connected to the source electrode.

In the present invention, the active matrix substrate may be an activematrix substrate including a plurality of source wirings, a plurality ofgate wirings and semiconductor elements on a (glass) substrate, in whichthe substrate includes an effective region where the semiconductorelements are formed and a periphery region in the periphery of theeffective region, and also includes a portion where the semiconductorelements disposed in the effective region are disposed on two groups ofequally spaced straight lines in the gate wiring direction and/or thesource wiring direction, and (second) semiconductor elements in theperipheral region are disposed on the above-mentioned groups of equallyspaced straight lines.

For example, as shown in FIG. 45-4, an active matrix substrate 213 inwhich TFTs 208 and 209 are formed near an intersection of a sourcewiring 192 with a gate wiring 193; the TFT 208 and the diode 210 arepositioned on a (first) group of equally spaced straight lines 211 inthe gate wiring direction; the TFT 209 is positioned on a (second) groupof equally spaced straight lines 212 in the gate wiring direction may beused. FIG. 45-4 is a planar view schematically showing a configurationof the active matrix substrate 213 according to Modified Embodiment ofthe present Embodiment. Semiconductor elements such as a TFT and a diodeother than the TFTs 208 and 209, and the diode 210 may be disposed atleast one of the effective region 195 and the peripheral region 196 onthe active matrix substrate 213, which is not shown in the figure. Ifthe methods used in Embodiments 1 to 6 and 10 are used, the TFTs 208 and209, and the diode 210 have semiconductor layers (amorphous siliconlayer and n⁺ type amorphous silicon layer) on the entire surface on thesubstrate side of the source electrode, the drain electrode, and thesource wiring connected to the source electrode.

In the present invention, the active matrix substrate may be an activematrix substrate including a plurality of source wirings, a plurality ofgate wirings and semiconductor elements on a (glass) substrate, in whichthe substrate includes an effective region where the semiconductorelements are formed and a periphery region in the periphery of theeffective region, and also includes a portion where the semiconductorelements disposed in the effective region are disposed on at least onegroup of equally spaced straight lines in the gate wiring directionand/or the source wiring direction, and (second) semiconductor elementsin the peripheral region are disposed on a group of straight linesdetermined based on a unit fraction of a distance between the equallyspaced straight lines.

For example, as shown in FIG. 45-5, an active matrix substrate 218including the TFTs 214 and diodes 217 in the periphery region on afourth group of equally spaced straight lines 216 formed separately froma third group of equally spaced straight lines 215 corresponding to thearray of the TFT 214 by a distance I2 may be used. If the distancebetween the straight lines constituting the third group of equallyspaced straight lines 215 on which the TFTs 214 are disposed is definedas I1, I2 is one third of I1. FIG. 45-5 is a planar view schematicallyshowing a configuration of the active matrix substrate 218 according toModified Embodiment of the present Embodiment. Semiconductor elementssuch as a TFT and a diode other than the TFT 214 and the diode 217 maybe disposed at least one of the effective region 195 and the peripheralregion 196 on the active matrix substrate 218, which is not shown in thefigure. If the methods mentioned in Embodiments 1 to 6 and 10 are used,the TFT 214 and the diode 217 have semiconductor layers (amorphoussilicon layer and n⁺ type amorphous silicon layer) on the entire surfaceon the substrate side of the source electrode, the drain electrode, andthe source wiring connected to the source electrode.

“Production of TFT Array Substrate”

Embodiment 12

The production method of the TFT array substrate (circuit substrate) inthe present Embodiment is a method in which the production methodsmentioned in Embodiments 1 to 6 are employed in combination with apublicly known conventional technology.

For example, the method of producing a TFT array substrate using theproduction method of the TFT shown in Embodiment 1 includes, as shown inFIG. 46, a gate electrode-forming step 311, a gate insulating film andsemiconductor film-forming step 312, a source metal film and resistfilm-forming step 313, a source metal film and semiconductorfilm-etching step 314, a resist film at channel-forming step 315, achannel-forming step 316, a passivation layer-forming step 317, and apixel electrode-forming step 318.

Among them, the gate electrode-forming step 311, the gate insulatingfilm and semiconductor film-forming step 312, the source metal film andresist film-forming step 313, the source metal film and semiconductorfilm-etching step 314, the resist film at channel-forming step 315, andthe channel-forming step 316 correspond to the gate electrode-formingstep 1, the gate insulating film and semiconductor film-forming step 2,the source metal film and resist film-forming step 3, the source metalfilm and semiconductor film-etching step 4, the resist film atchannel-forming step 5, and the channel-forming step 6 in Embodiment 1,respectively. TFT or a TFT part in a diode (TFD) and the like is formedby the method mentioned in Embodiment 1. Other parts, for example,terminal parts in the peripheral region and other electrical contactparts may be formed according to a conventional technology.

The passivation layer-forming step 317 and the pixel electrode-formingstep 318 are performed by a conventional technology. In the passivationlayer-forming step 17, a silicon nitride film which serves as apassivation layer later is formed by a plasma enhanced CVD method andprocessed into a specific pattern by photolithography. As a result, apassivation layer for protecting the TFT and the like is obtained. Inthe pixel electrode-forming step, an ITO film which serves as a pixelelectrode later by a sputtering method is formed and processed into aspecific pattern by photolithography. As a result, a pixel electrodeused in image display and the like is obtained.

Similarly, a TFT array substrate may be produced using the productionmethods of the TFT mentioned in Embodiments 2 to 6 and a conventionaltechnology in combination.

The shapes mentioned in Embodiments 7 to 10 may be used as those of theTFT and the TFD.

This Nonprovisional application claims priority (under 35 U.S.C. §119)on Patent Application No. 2005-133244 filed in Japan on Apr. 28, 2005,the entire contents of which are hereby incorporated by reference.

The terms “or more” and “or less” include the described values,respectively.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flowchart showing order of the production steps of the TFTaccording to Embodiment 1 of the present invention.

FIG. 2( a) is a planer view schematically showing the TFT produced bythe production method of Embodiment 1 and a configuration near the TFT;and FIG. 2( b) is a cross-sectional view schematically showing theconfiguration taken along line A-A in FIG. 2( a).

FIG. 3 is a perspective view schematically showing a structure of anink-jet device.

FIG. 4( a) is a planar view schematically showing a configuration afterthe gate electrode-forming step 1 in the production process of the TFT7; and FIG. 4( b) is a cross-sectional view schematically showing theconfiguration taken along line B-B in FIG. 4( a) (Embodiment 1).

FIG. 5( a) is a planar view schematically showing a state after the gateinsulating film and semiconductor film-forming step 2 in the productionprocess of the TFT 7; and FIG. 5( b) is a cross-sectional viewschematically showing the configuration taken along line C-C in FIG. 5(b) (Embodiment 1).

FIG. 6( a) is a cross-sectional view schematically showing a state afterthe source metal film and resist film-forming step in the productionprocess of the TFT 7; and FIG. 6( b) is a cross-sectional viewschematically showing the configuration taken along line D-D in FIG. 6(a) (Embodiment 1).

FIG. 7( a) is a cross-sectional view schematically showing a state afterthe source metal film and semiconductor film-etching step 4 in theproduction process of the TFT 7; and FIG. 7( b) is a cross-sectionalview schematically showing the configuration taken along line E-E inFIG. 7( a) (Embodiment 1).

FIG. 8( a) is a planar view schematically showing a state where a resistdroplet has just landed on the TFT gap 31; FIG. 8( b) is across-sectional view schematically showing the configuration taken alongline F-F in FIG. 8( a) (Embodiment 1).

FIG. 9( a) is a planar view schematically showing a state where theresist droplet 32 shown in FIG. 8( a) is deformed because of itsfluidity after landed; and FIG. 9( b) is a cross-sectional viewschematically showing the configuration taken along line G-G in FIG. 9(a) (Embodiment 1).

FIG. 10( a) is a planar view schematically showing a state where theresist pattern film 35 is formed inside the TFT gap 31; and FIG. 10( b)is a cross-sectional view schematically showing the configuration takenalong line H-H in FIG. 10( a) (Embodiment 1).

FIG. 11( a) is a planar view schematically showing a state after thechannel-forming step 6 in the production process of the TFT 7; and FIG.11( b) is across-sectional view schematically showing the configurationtaken along line I-I in FIG. 11( a).

FIG. 12 is a flowchart showing order of the production steps of the TFTaccording to Comparative Embodiment 1.

FIG. 13( a) is a planer view schematically showing the TFT prepared bythe production method of Comparative Embodiment 1 and a configurationnear the TFT; and FIG. 13( b) is a cross-sectional view schematicallyshowing the configuration taken along line J-J in FIG. 13( a).

FIG. 14( a) is a planar view schematically showing a configuration ofthe TFT prepared by the production method in Patent Document 5; and FIG.14( b) is a cross-sectional view schematically showing the configurationtaken along line K-K in FIG. 14( a).

FIG. 15( a) is a planar view schematically showing a configuration ofthe TFT prepared by the production method in Patent Document 5; and FIG.15( b) is a cross-sectional view schematically showing the configurationtaken along line L-L in FIG. 15( a).

FIG. 16 is an enlarged planar view schematically showing a part aftercompletion of the source metal film and semiconductor film-etching step4 in Embodiment 1 (FIG. 7( a)).

FIG. 17( a) is a planar view schematically showing a state where theresist pattern film 74 slightly flows out of the TFT gap 31 and is alsoformed on the upper part of the resist pattern film 30; and FIG. 17( b)is a cross-sectional view schematically showing the configuration takenalong line M-M in FIG. 17( a) (Modified Embodiment of Embodiment 1).

FIG. 18( a) is a planar view schematically showing a state where theresist pattern film 75 is formed only near the center of the TFT gap 31;and FIG. 18( b) is a cross-sectional view schematically showing theconfiguration taken along line N-N in FIG. 18( a) (Modified Embodimentof Embodiment 1).

FIG. 19( a) is a planar view schematically showing a state where thelyophilic or lyophobic film 76 remains at the TFT gap 31; and FIG. 19(b) is a cross-sectional view schematically showing the configurationtaken along line O-O in FIG. 19( a).

FIG. 20 is a flowchart showing order of the production steps of the TFTaccording to Embodiment 2 of the present invention.

FIG. 21( a) is a planar view schematically showing a state aftercompletion of the source metal film and semiconductor film-etching step81 is completed; and FIG. 21( b) is a cross-sectional view schematicallyshowing the configuration taken along line P-P in FIG. 21( a).

FIG. 22( a) is a planar view schematically showing a state aftercompletion of the resist film at channel-forming step 82; and FIG. 22(b) is a cross-sectional view schematically showing the configurationtaken along line Q-Q in FIG. 22( a).

FIG. 23 is a flowchart showing order of the production steps of the TFTaccording to Embodiment 3 of the present invention.

FIG. 24( a) is a planar view schematically showing the TFT prepared inEmbodiment 3 and a configuration near the TFT; and FIG. 24( b) is across-sectional view schematically showing the configuration taken alongline R-R in FIG. 24( a).

FIG. 25( a) is a planar view schematically showing a state aftercompletion of the source metal film and semiconductor film-etching andpassivation film-forming step 91; and FIG. 25( b) is a cross-sectionalview schematically showing the configuration taken along line S-S inFIG. 25( a) (Embodiment 3).

FIG. 26( a) is a planar view schematically showing a state aftercompletion of the resist film at channel-forming step 92; and FIG. 26(b) is a cross-sectional view schematically showing the configurationtaken along line T-T in FIG. 26( a) (Embodiment 3).

FIG. 27 is a flowchart showing order of the production steps of the TFTaccording to Embodiment 4 of the present invention.

FIG. 28( a) is a planar view schematically showing a state aftercompletion of the resist film at channel-forming step 101; and FIG. 28(b) is a cross-sectional view schematically showing the configurationtaken along line U-U in FIG. 28( a) (Embodiment 4).

FIG. 29 is a flowchart showing order of the production steps of the TFTaccording to Embodiment 5 of the present invention.

FIG. 30( a) is a cross-sectional view schematically showing a stateafter completion of landing of the solvent droplet; and FIG. 30( b) is across-sectional view schematically showing the configuration taken alongline V-V in FIG. 30( a).

FIG. 31( a) is a planar view schematically showing a state where theresist pattern film 115 is formed inside the TFT gap 31; and FIG. 31( b)is a cross-sectional view schematically showing the configuration takenalong line W-W in FIG. 31( a) (Embodiment 5).

FIG. 32 is a flowchart showing order of the production steps of the TFTaccording to Embodiment 6 of the present invention.

FIG. 33( a) is a planar view schematically showing a configuration ofthe TFT 302 produced in Embodiment 6; and FIG. 33( b) is across-sectional view schematically showing the configuration taken alongline AF-AF in FIG. 33( a).

FIG. 34( a) is a planar view schematically showing a substrateimmediately after the back surface exposure; FIG. 34( b) is across-sectional view schematically showing the configuration taken alongline AG-AG in FIG. 34( a) (Embodiment 6).

FIG. 35( a) is a planar view schematically showing a substrate after thedevelopment treatment; and FIG. 35( b) is a cross-sectional viewschematically showing the substrate taken along line AH-AH in FIG. 35(a) (Embodiment 6).

FIG. 36-1( a) is a planar view schematically showing one example of theconfiguration of the TFT according to Embodiment 7; and FIG. 36-1( b) isa cross-sectional view schematically showing the TFT taken along lineX-X in FIG. 36-1( a).

FIG. 36-2( a) is a planar view schematically showing another example ofthe configuration of the TFT in Embodiment 7; and FIG. 36-2( b) is across-sectional view schematically showing the TFT taken along line Y-Yin FIG. 36-2( b).

FIG. 37( a) is a planar view schematically showing a configuration ofthe TFT according to Embodiment 8; and FIG. 37( b) is a cross-sectionalview schematically showing the TFT taken along line Z-Z in FIG. 37( a).

FIG. 38 is an enlarged view of the source electrode 127 and the drainelectrode 126 in FIG. 37( a) (Embodiment 8).

FIG. 39( a) is a planar view schematically showing a configuration ofthe TFT 128 according to an embodiment in which the configuration whereat least one of the source electrode and the drain electrode has a notchin Embodiment 7 and the configuration where the channel has a squaredU-shape or a U-shape in Embodiment 8 are combined; and FIG. 39( b) isacross-sectional view schematically showing the TFT taken along lineAA-AA in FIG. 39( a).

FIG. 40( a) is a planar view schematically showing a configuration ofthe TFT 131 according to an embodiment in which the configuration whereat least one of the source electrode and the drain electrode inEmbodiment 7 have a notch, and the configuration where the channel inEmbodiment 8 has a squared U-shape or a U-shape are combined; and FIG.40( b) is a cross-sectional view schematically showing the TFT takenalong line AB-AB in FIG. 40( a).

FIG. 41( a) is an enlarged view showing the source electrode 15 and thelike in FIG. 2( a); and FIG. 41( b) is an enlarged view showing thesource electrode 149 and the like of the TFT produced by the method inEmbodiment 1, for comparison with FIG. 41( a) (Embodiment 9).

FIG. 42( a) is a planar view schematically showing a configuration ofthe TFT 158 according to an embodiment in which the configuration wherethe channel in Embodiment 8 has a squared U-shape or a U-shape and theconfiguration where the source electrode and the drain electrode havecorners near every end of the TFT channel part are combined; and FIG.42( b) is a cross-sectional view schematically showing the TFT takenalong line AC-AC in FIG. 42( a).

FIG. 43( a) is a planar view schematically showing the diode and aconfiguration near the diode according to Embodiment 10; and FIG. 43( b)is a cross-sectional view schematically showing the configuration takenalong line AD-AD.

FIG. 44( a) is a planar view schematically showing the diode and aconfiguration near the diode according to Modified Embodiment ofEmbodiment 10; and FIG. 44( b) is a cross-sectional view schematicallyshowing the configuration taken along line AE-AE.

FIG. 45-1 is a planar view schematically showing one example of theconfiguration of the active matrix substrate according to Embodiment 11.

FIG. 45-2 is a planar view schematically showing one example of theconfiguration of the active matrix substrate according to Embodiment 11.

FIG. 45-3 is a planar view schematically showing one example of theconfiguration of the active matrix substrate according to Embodiment 11.

FIG. 45-4 is a planar view schematically showing one example of theconfiguration of the active matrix substrate according to Embodiment 11.

FIG. 45-5 is a planar view schematically showing one example of theconfiguration of the active matrix substrate according to Embodiment 11.

FIG. 46 is a flowchart showing order of the production step of the TFTarray substrate (substrate for display device) according to Embodiment12 of the present invention.

EXPLANATION OF NUMERALS AND SYMBOLS

-   1: Gate electrode-forming step-   2: Gate insulating film and semiconductor film-forming step-   3: Source metal film and resist film-forming step-   4: Source metal film and semiconductor film-etching step-   5: Resist film at channel-forming step-   6: Channel-forming step-   7: TFT-   8: Glass substrate-   9: Gate wiring-   10: Gate electrode-   11: Gate insulating film-   12: Amorphous silicon layer-   13: N⁺ type amorphous silicon layer-   14: Source wiring-   15: Source electrode-   16: Drain connecting wiring-   17: Drain electrode-   18: TFT channel-   19: Substrate-   20: Mounting base-   21: Ink-jet head-   22: X direction driving part-   23: Y direction driving part-   24: Ink feed system-   25: Control unit-   27: Amorphous silicon film-   28: N⁺ type amorphous silicon film-   29: Source metal film-   30: Resist pattern film-   31: TFT gap-   32: Resist droplet-   33: Resist droplet-   34: Both ends of TFT gap-   35: Resist pattern film-   41: Gate electrode-forming step-   42: Gate insulating film and semiconductor film-forming step-   43: Resist film for semiconductor film process-forming step-   44: Semiconductor island-forming step-   45: Source metal film and resist film-forming step-   46: Source metal film and semiconductor film-etching step-   47: TFT-   48: Glass substrate-   49: Gate wiring-   50: Gate electrode-   51: Gate insulating film-   52: Amorphous silicon layer-   53: N⁺ type amorphous silicon layer-   54: Source wiring-   55: Source electrode-   56: Drain connecting wiring-   57: Drain electrode-   58: TFT channel-   61: TFT-   62: Glass substrate-   63: Gate electrode-   64: Gate insulating film-   65: Amorphous silicon layer-   66: Source electrode-   67: Drain electrode-   68: N⁺ amorphous silicon layer-   69: Shaded region-   70: TFT-   71: Amorphous silicon layer-   72: Shaded region-   73: N⁺ type amorphous silicon layer-   74: Resist pattern film-   75: Resist pattern film-   76: Lyophilic or lyophobic film-   81: Source metal film and semiconductor film-etching step-   82: Resist film at channel-forming step-   83: Channel-forming step-   84: Resist pattern film-   91: Source metal film and semiconductor film-etching and passivation    film-forming step-   92: Resist film at channel-forming step-   93: Channel-forming step-   94: TFT-   95: TFT channel-   96: Passivation layer-   97: Silicon nitride film (passivation film)-   98: TFT gap-   99: Resist pattern film-   101: Resist film at channel-forming step-   102: Source metal film and semiconductor film-etching step-   103: Resist film at channel-removing step-   104: Channel-processing step-   105: TFT gap-   106: Resist pattern film-   111: Source metal film and semiconductor film-etching step-   112: Resist film at channel-forming step-   113: Channel-forming step-   114: Solvent droplet-   115: Resist pattern film-   116: Resist pattern film-   121: TFT-   122: Drain electrode-   123: TFT-   124: Drain electrode-   125: TFT-   126: Drain electrode-   127: Source electrode-   128: TFT-   129: Drain electrode-   130: Source electrode-   131: TFT-   132: Drain electrode-   133: Source electrode-   141: End of TFT channel 18-   142: End of TFT channel 18-   143: Corner of source electrode 15-   144: Corner of drain electrode 17-   145: Corner of source electrode 15-   146: Corner of drain electrode 17-   147: TFT-   148: Source wiring-   149: Source electrode-   150: Drain connecting wiring-   151: Drain electrode-   152: TFT channel-   153: End of TFT channel 152-   154: End of TFT channel 152-   155: Corner of source electrode 149-   156: Corner of drain electrode 151-   157: Corner of source electrode 149-   158: TFT-   159: TFT channel-   160: Region-   171: Diode-   172: Glass substrate-   173: Gate electrode-   174: Gate insulating film-   175: Amorphous silicone layer-   176: N⁺ type amorphous silicone layer-   177: Connecting wiring-   178: Drain electrode-   179: Connecting wiring-   180: Source electrode-   181: Passivation film-   182: Conductive film for connection-   183: Channel-   184: Contact part-   185: TFT-   186: Diode-   187: Contact-   188: Conductive film for connection-   189: TFT-   191: Active matrix substrate-   192: Source wiring-   193: Gate wiring-   194: TFT-   195: Effective region (shaded portion)-   196: Peripheral region-   197: Diode-   198: Group of straight lines-   199: TFT-   200: Diode-   201: Group of straight lines-   202: Active matrix substrate-   203: TFT-   204: TFT-   205: Diode-   206: Group of straight lines-   207: Active matrix substrate-   208: TFT-   209: TFT-   210: Diode-   211: First group of equally spaced straight lines-   212: Second group of equally spaced straight lines-   213: Active matrix substrate-   214: TFT-   215: Third group of equally spaced straight lines-   216: Fourth group of equally spaced straight lines-   217: Diode-   218: Active matrix substrate-   301: Channel resist film-forming step-   302: TFT-   303: Gate electrode-   304: TFT channel-   305: Both ends of TFT channel-   306: Region exposed to diffracted light due to back surface exposure-   307: Resist pattern film-   311: Gate electrode-forming step-   312: Gate insulating film and semiconductor film-forming step-   313: Source metal film and resist film-forming step-   314: Source metal film and semiconductor film-etching step-   315: Channel resist film-forming step-   316: Channel-forming step-   317: Passivation layer-forming step-   318: Pixel electrode-forming step

1. A production method of a pattern thin film, comprising the steps of:forming a first resist pattern film on a thin film formed on asubstrate; removing a part of the thin film using the first resistpattern film; forming a second resist pattern film by applying a fluidresist material on a groove of a bank pattern in the first resistpattern film; and patterning the thin film using at least the secondresist pattern film.
 2. The production method of the pattern thin filmaccording to claim 1, wherein the bank pattern has an open end.
 3. Theproduction method of the pattern thin film according to claim 1, whereinthe thin film formed on the substrate includes two or more layers. 4.The production method of the pattern thin film according to claim 1,wherein in the step of forming the first resist pattern film, a resistmaterial having photosensitivity is used and exposure is performed usinga photomask.
 5. The production method of the pattern thin film accordingto claim 1, comprising a plasma surface treatment step between the stepof forming the first resist pattern film and the step of forming thesecond resist pattern film.
 6. The production method of the pattern thinfilm according to claim 5, wherein the plasma surface treatment step isperformed in fluorine gas plasma.
 7. The production method of thepattern thin film according to claim 1, comprising a step of patterningthe thin film using the first resist pattern film between the step offorming the first resist pattern film and the step of forming the secondresist pattern film.
 8. The production method of the pattern thin filmaccording to claim 7, wherein the step of patterning the thin film usingthe first resist pattern film is performed by a dry-etching method. 9.The production method of the pattern thin film according to claim 7,comprising a step of removing the first resist pattern film between thestep of patterning the thin film using the first resist pattern film andthe step of forming the second resist pattern film.
 10. The productionmethod of the pattern thin film according to claim 1, further comprisingthe steps of after the step of forming the first resist pattern film andthe step of forming the second resist pattern film, patterning the thinfilm using the first resist pattern film and the second resist patternfilm; and removing the second resist pattern film.
 11. The productionmethod of the pattern thin film according to claim 1, wherein in thestep of forming the second resist pattern film, the fluid resistmaterial is applied using an application device including a multi-nozzleinjection head and a substrate stage.
 12. The production method of thepattern thin film according to claim 11, wherein the application deviceis an ink-jet device.
 13. The production method of the pattern thin filmaccording to claim 12, wherein the fluid resist material contains atleast one ether, ester, diester, and/or ether ester selected from thegroup consisting of an ethylene glycol, a diethylene glycol, atriethylene glycol, a polyethylene glycol, a propylene glycol, adipropylene glycol, a tripropylene glycol, a polypropylene glycol, and abutylene glycol, or a hydrocarbon, having a boiling point of 180° C. ormore at 1 atmosphere.
 14. The production method of the pattern thin filmaccording to claim 13, wherein the fluid resist material containsnovolak resin.
 15. The production method of the pattern thin filmaccording to claim 12, wherein the fluid resist material containsnovolak resin, and at least one ether, ester, diester, and/or etherester selected from the group consisting of an ethylene glycol, adiethylene glycol, a triethylene glycol, a polyethylene glycol, apropylene glycol, a dipropylene glycol, a tripropylene glycol, apolypropylene glycol, and a butylene glycol, or a hydrocarbon.
 16. Theproduction method according to claim 1, wherein a semiconductor layer, asource electrode, and a drain electrode are formed by patterning asemiconductor film and a metal film formed on the substrate.
 17. Aproduction method of a pattern thin film, comprising: forming a firstresist pattern film on a thin film formed on a substrate wherein thefirst resist pattern film creates a bank pattern; forming a secondresist pattern film distinct from the first resist pattern film byapplying a fluid resist material in a through of the bank pattern of thefirst resist pattern film; reshaping the second resist pattern to form asubstantially concave film surface within the trough; and patterning thethin film using at least the reshaped second resist pattern film.